Sunroof

Sunroof (pronounced suhn-roof)

(1) A section of an automobile roof (sometimes translucent and historically called a moonroof) which can be slid or lifted open.

(2) In obstetrics, a slang term used by surgeons to describe the Caesarean section.

1952: A compound word, the construct being sun + roof.  Sun was from the Middle English sonne & sunne, from the Old English sunne, from the Proto-West Germanic sunnā, from the Proto-Germanic sunnǭ, from the primitive Indo-European shwen-, oblique of sóhw (sun).  The other forms from the Germanic included the Saterland Frisian Sunne, the West Frisian sinne, the German Low German Sünn, the Dutch zon, the German Sonne and the Icelandic sunna.  The forms which emerged without Germanic influence included the Welsh huan, the Sanskrit स्वर् (svar) and the Avestan xᵛə̄ṇg.  The related forms were sol, Sol, Surya and Helios.  Roof was from the Middle English rof, from the Old English hrōf (roof, ceiling; top, summit; heaven, sky), from the Proto-Germanic hrōfą (roof).  Throughout the English-speaking world, roofs is now the standard plural form of roof.  Rooves does have some history but has long been thought archaic and the idea there would be something to be gained from maintaining rooves as the plural to avoid confusion with roof’s the possessive never received much support.  Despite all that, rooves does seem to appear more than might be expected, presumably because there’s much more tolerance extended to the irregular plural hooves but the lexicographers are unimpressed and insist the model to follow is poof (an onomatopoeia describing a very small explosion, accompanied usually by a puff of smoke), more than one poof correctly being “poofs”.  In use, a poof was understood as a small event but that's obviously a spectrum and some poofs would have been larger than others so it would have been a matter of judgement when something ceased to be a “big poof” and was classed an explosion proper.  Sunroof is a noun (sometimes hyphenated); the noun plural is sunroofs.

1973 Lincoln Continental Mark IV with moonroof.

Sunroofs existed long before 1952 but that was the year the word seems first to have been adopted by manufacturers in Detroit.  The early sunroofs were folding fabric but metal units, increasingly electrically operated, were more prevalent by the early 1970s.  Ford, in 1973, introduced the word moonroof (which was used also as moon roof & moon-roof) to describe the sliding pane of one-way glass mounted in the roof panel over the passenger compartment of the Lincoln Continental Mark IV (1972-1976).  Moonroof soon came to describe any translucent roof panel, fixed or sliding though the term faded from use and all such things tend now to be thought sunroofs.

Open (left) and shut (centre) case: 1976 Lincoln Continental Mark IV (right) with Moonroof.

According to Ford in 1973, a “sunroof” was an opening in the roof with a sliding hatch made from a non-translucent material (metal or vinyl) while a “moonroof” included a hatch made from a transparent or semi-transparent substance (typically then glass).  The advantage the moonroof offered was additional natural light could be enjoyed even if the weather (rain, temperature etc) precluded opening the hatch.  A secondary, internal, sliding hatch (really an extension of the roof lining) enabled the sun to be blocked out if desired and in that configuration the cabin’s ambiance would be the same whether equipped with sunroof, moonroof or no sliding mechanism of any kind.  Advances in materials mean many of what now commonly are called “sunroofs” are (by Ford’s 1973 definition) really moonroofs but use of the latter term is now rare.

Lindsay Lohan standing through a sunroof: Promotional photo-shoot for Herbie Fully Loaded (2005).

Unlike many manufacturers, for many years Volkswagen maintained specific “Sunroof” models in the Beetle (Type 1) range.  When in 1945 the British military occupation forces assumed control of the Volkswagen factory and commenced production of civilian models (those made since 1938 delivered almost exclusively to the German armed forces or Nazi Party functionaries), one of the first organizational changes was to replace Herr Professor Ferdinand Porsche’s (1875–1951) internal type designations with a new set and these included the 115 (Standard Beetle Sunroof Sedan (LHD (left-hand drive)), 116 (Standard Beetle Sunroof Sedan (RHD (right-hand drive)), 117 (Export Deluxe Beetle Sunroof Sedan (LHD) & Export Deluxe Beetle Sunroof Sedan (RHD).  The original sunroof was a folding, fabric apparatus and this remained in use until 1963, a steel, sliding (manually hand-cranked) unit was fitted after the release of the 1964 range.  The Beetle used in the original film (The Love Bug (1968)) was a 1963 Sunroof Beetle; at the time they were readily available at low cost but by 2004-2005 when Herbie: Fully Loaded was in production, they were less numerous and some of those used in the filming were actually 1961 models modified (to the extent required in movies) for purposes of continuity.  Interestingly, the one which appears in most scenes appears to be a 1964 model which implies the folding sunroof was at some point added, not difficult because the kits have long been available.

Caesarean section post-operative scar: C-section scar revision is now a commonly performed procedure.

Manufacturers in the 1970s allocated resources to refine the sunroof because, at the time, the industry’s assumption was the implications of the US NHTSA's (National Highway Traffic Safety Administration) FMVSS (Federal Motor Vehicle Safety Standards) 208 (roll-over protection, published 1970) fully would be realized, outlawing both convertibles and hardtops (certainly the four-door versions).  FMVSS 208 was slated to take effect in late 1975 (when production began of passenger vehicles for the 1976 season) with FMVSS 216 (roof-crush standards) added in 1971 and applying to 1974-onwards models.  There was a “transitional” exemption for convertibles but it ran only until August 1977 (a date agreed with the industry because by then Detroit’s existing convertible lines were scheduled to have reached their EoL (end of life)) at which point the roll-over and roof-crush standards universally would be applied to passenger vehicles meaning the only way a “convertible” could registered for use on public roads was if it was some interpretation of the “targa” concept (Porsche 911, Chevrolet Corvette etc), included what was, in effect a roll-cage (Triumph Stag) or (then more speculatively), some sort of device which in the event of a roll-over would automatically be activated to afford occupants the mandated level of protection and Mercedes-Benz later would include such a device on the R129 SL roadster (1998-2001).  Although in 1988 there were not yet “pop-ups” on the internet to annoy us, quickly the press dubbed the R129’s innovative safety feature a “pop-up roll bar”, the factory called the apparatus automatischer Überrollbügel (automatic rollover bar).  It was spring loaded and pyrotechnically activated, designed fully to deploy in less than a half-second if sensors detected an impending rollover although the safety-conscious could at any time raise it by pressing one of the R129’s many buttons.

Alternative approaches (partial toplessness): 1973 Triumph Stag in Magenta (left) and 1972 Porsche 911 Targa in silver (right).  The lovely but flawed Stag (1970-1977) actually needed its built-in roll cage for structural rigidity because it's underpinnings substantially were unchanged from the Triumph 2000 sedan (1963-1977) on which it was based.

Despite the myths which grew to surround the temporary extinction of convertibles from Detroit’s production lines, at the time, the industry was at best indifferent about their demise and happily would have offered immediately to kill the breed as a trade-off for a relaxation or abandonment of other looming safety standards.  As motoring conditions changed and the cost of installing air-conditioning fell, convertible sales had since the mid-1960s been in decline and the availability of the style had been pruned from many lines.  Because of the additional engineering required (strengthening the platform, elaborate folding roofs with electric motors), keeping them in the range was justifiable only if volumes were high and it was obvious to all the trend was downwards, thus the industry being sanguine about the species loss.  That attitude didn’t however extend to a number of British and European manufacturers which had since the early post-war years found the US market a place both receptive and lucrative for their roadsters and cabriolets; for some, their presence in the US was sustained only by drop-top sales.  By the 1970s, the very existence of the charming (if antiquated) MG & Triumph roadsters was predicated upon US sales.

High tech approach (prophylactic toplessness): Mercedes-Benz advertising for the R129 roadster (in the factory's Sicherheitsorange (safety orange) used for test vehicles).

The play on words uses the German wunderbar (“wonderful” and pronounced vuhn-dah-baah) with a placement and context so an English speaking audience would read the word as “wonder bar”; it made for better advertising copy than the heading: Automatischer Überrollbügel.  This was a time when the corporate tag-line “Engineered like no other car” was still a reasonable assertion.  It had been the spectre of US legislation which accounted for Mercedes-Benz not including a cabriolet when the S-Class (W116) was released in 1972, leaving the SL (R107; 1971-1989) roadster as the company’s only open car and it wasn’t until 1990 a four-seat cabriolet returned with the debut of the A124. 

Chrysler was already in the courts to attempt to have a number of the upcoming regulations (focusing on those for which compliance would be most costly, particularly barrier crash and passive safety requirements) so instead of filing their own suit, a consortium of foreign manufacturers (including British Leyland & Fiat) sought to “append themselves” to the case, lodging a petition seeking judicial review of roll-over and roof-crush standards, arguing that in their present form (ie FMVSS 208 & 216), their application unfairly would render unlawful the convertible category (on which the profitability of their US operation depended).  A federal appeals court late in 1972 agreed and referred the matter back to NHTSA for revision, ordering the agency to ensure the standard “…does not in fact serve to eliminate convertibles and sports cars from the United States new car market.”  The court’s edit was the basis for the NHTSA making convertibles permanently exempt from roll-over & roof crush regulations.  That ensured the foreign roadsters & cabriolets lived on but although the ruling would have enabled Detroit to remain in the market, it regarded the segment as one in apparently terminal decline and had no interest in allocating resources to develop new models, happily letting existing lines expire.

The “last American convertible” ceremony, Cadillac Clark Street Assembly Plant, Detroit, Michigan, 21 April 1976.

One potential “special case” may have been the Cadillac Eldorado which by 1975 was the only one of the few big US convertibles still available selling in reasonable numbers but the platform was in its final years and with no guarantee a version based on the new, smaller Eldorado (to debut in 1978) would enjoy similar success, General Motors (GM) decided it wasn’t worth the trouble but, sensing a “market opportunity”, promoted the 1976 model as the “Last American convertible”.  Sales spiked, some to buyers who purchased the things as investments, assuming in years to come they’d have a collectable and book a tidy profit on-selling to those who wanted a (no longer available) big drop-top.  Not only did GM use the phrase as a marketing hook; when the last of the 1976 run rolled off the Detroit production line on 21 April, the PR department, having recognized a photo opportunity, conducted a ceremony, complete with a “THE END OF AN ERA 1916-1976”) banner and a “LAST” Michigan license plate.  The final 200 Fleetwood Eldorado convertibles were “white on white on white”, identically finished in white with white soft-tops, white leather seat trim with red piping, white wheel covers, red carpeting & a red instrument panel; red and blue hood (bonnet) accent stripes marked the nation’s bicentennial year.

The “last American convertible” ceremony, Cadillac Clark Street Assembly Plant, Detroit, Michigan, 21 April 1976.

Of course in 1984 a convertible returned to the Cadillac catalogue so some of those who had stashed away their 1976 models under wraps in climate controlled garages weren’t best pleased and litigation ensued, a class action filed against GM alleging the use of the (now clearly incorrect) phrase “Last American Convertible” had been “deceptive or misleading” in that it induced the plaintiffs to enter a contract which they’d not otherwise have undertaken.  The suit was dismissed on the basis of there being insufficient legal grounds to support the claim, the court ruling the phrase was a “non-actionable opinion” rather than a “factual claim”, supporting GM's contention it had been a creative expression rather than a strict statement of fact and thus did not fulfil the criteria for a “deceptive advertising” violation.  Additionally, the court found there was no actual harm caused to the class of plaintiffs as they failed to show they had suffered economic loss or that the advertisement had led them to make a purchase they would not otherwise have made.  That aspect of the judgment has since been criticized with dark hints it was one of those “what’s good for General Motors is good for the country” moments but the documentary evidence did suggest GM at the time genuinely believed the statement to be true and no action was possible against the government on several grounds, including the doctrines of remoteness and unforeseeability.

Ronald Reagan (1911-2004, US president 1981-1989). in riding boots & spurs with 1938 LaSalle Series 50 Convertible Coupe (one of 819 produced that year), Warner Brothers Studios, Burbank California, 1941.  

LaSalle was the lower-priced (although marketed more as "sporty") "companion marque" to Cadillac and a survivor of GM's (Great Depression-induced) 1931 cull of brand-names, the last LaSalle produced in 1940.  Mr Regan remained fond of Cadillacs and when president was instrumental is shifting the White House's presidential fleet to them from Lincolns.  Although doubtlessly Mr Reagan had fond memories of top-down motoring in sunny California (climate change not yet making things too hot, too often for them to be enjoyed in summer) and was a champion (for better and worse) of de-regulation, it's an urban myth he lobbied to ensure convertibles weren't banned in the US.  

Following Lindsay Lohan's example: President Xi standing through a sunroof, reviewing military parade in Hongqi L5 state limousine, Beijing, 2019.

The highlight of the ceremonies marking the 70^th anniversary of the founding of the People's Republic of China (PRC) was the military parade, held in Beijing on 1 October 2019.  Claimed to be the largest military parade and mass pageant in China's 4,000-odd year history (and the last mass gathering in China prior to the outbreak in Wuhan of became the COVID-19 pandemic), the formations were reviewed by the ruling Chinese Communist Party’s (CCP) General Secretary Xi Jinping (b 1953; paramount leader of the PRC since 2012).  The assembled crowd was said without exception to be “enthusiastic and happy” and the general secretary's conspicuously well-cut Mao suit was a nice nostalgic touch.

Two generals of the Belarus army take the salute standing, in Honggi L5 Parade Convertibles, Minsk, Belarus, June 2017.

Independence Day in Belarus is celebrated annually on 3 June and there is always a significant military component.  Other than the PRC, Belarus is the only known operator of the Honqqi and the four-door convertible parade cars were apparently a "gift" (as opposed to foreign aid) from the Chinese government but the aspect of this photograph which attracted some comment was whether the hats worn by generals in Belarus were bigger than the famously imposing headwear of the army of the DPRK (Democratic People’s Republic of Korea (North Korea)); analysts of military millinery appeared to conclude the dimensions were similar.  Purists traditionally describe this style of coach-work as "four-door cabriolet" and it was "Cabriolet D" in the Daimler-Benz system but the "parade convertible" is a distinct breed and often includes features such as grab bars for those standing, microphones and loud-speakers so the “enthusiastic and happy” crowd miss not one word.   

Hongqi L5 state limousine.

The car carrying President Xi was the Hongqi L5, the state limousine of the PRC, the coachwork styling a deliberately retro homage to the Hongqi CA770, the last in the line (dating from 1958) of large cars built almost exclusively for use by the upper echelons of the CCP.  Most of the earlier cars were built on the large platforms US manufacturers used in the 1960s and were powered by a variety of US-sourced V8 engines but the L5 was wholly an indigenous product, built with both a 6.0 litre (365 cubic inch) V12 and 4.0 litre (245 cubic inch) V8 although neither configuration is intended for high-performance.  Interestingly, although Hongqi L5 have produced a version of the L5 with four-door convertible coachwork as a formal parade car and they have been used both in the PRC and in Belarus, the general secretary conducted his review in a closed vehicle with a sunroof.

US President Richard Nixon (1913-1994, US president 1969-1974) with Anwar Sadat (1918–1981; President of Egypt 1970-1981) in a 1967 Cadillac convertible, Alexandria, Egypt, June 1974.  On that day, the motorcade was 180-strong and unlike the reception his appearance in the US now induced, the Egyptian crowd really did seem genuinely enthusiastic and happy.  Within two months, in disgrace because of his part in the Watergate Affair, Nixon would resign.

The CCP didn’t comment on the choice of a car with a sunroof and it may have been made on technical grounds, the provision of a microphone array presumably easier with the roof available as a mounting point and given the motorcade travelled a higher speed than a traditional parade, it would also have provided a more stable platform for the general secretary.  It’s not thought there was any concern about security, Xi Jinping (for a variety of reasons) safer in his capital than many leaders although heads of state and government became notably more reticent about travelling in open-topped vehicles after John Kennedy (1917–1963; US president 1961-1963) was assassinated in 1963.  Some, perhaps encouraged by Richard Nixon being greeted by cheering crowds in 1974 when driven through the streets of Alexandria (a potent reminder of how things have changed) in a Cadillac convertible, persisted but after the attempt on the life of John Paul II (1920–2005; pope 1978-2005) in 1981, there’s been a trend to roofs all the way, sometimes molded in translucent materials of increasing chemical complexity to afford some protection from assassins.

Military parade marking the 70^th anniversary of the founding of the PRC, Beijing, China, 1 October 2019.  Great set-piece military parades like those conducted by the PRC and DPRK (recalling the spectacles staged by both Nazi Germany (1933-1945) and the Soviet Union (1922-1991) are now packaged for television and distribution on streaming platforms and it may be Donald Trump (b 1946; US president 2017-2021 and since 2025) was hoping the "Grand Military Parade" he scheduled in 2025 for his 79^th birthday (ostensibly to celebrate 250 years since the formation of the US Army) would display the same impressive precision in chorography.     

Covering all possibilities during the 24 hour cycle.  US advertisement (1974) for the Renault 17 Gordini Coupe Convertible, the Gordini tag adopted as a "re-brand" of the top-of-the-range R17 (1971-1979).  Gordini was a French sports car producer and tuning house, absorbed by Renault in 1968, the name from time-to-time used for high-performance variants of various Renault models.

Renault over the decades made the occasional foray into the tempting US market but all ended badly in one way or another, their products, whatever their sometimes real virtues, tending not to be suited to US driving habits and conditions.  Sunroofs had long been popular in Europe and, noting (1) what was assumed to be the demise of the convertible and (2) Lincoln's coining of "moon roof", Renault decided Americans deserved a sunroof, moonroof & starroof, all in one.  Actually, they got even more because there was also a removable, fibreglass hardtop for the winter months, Renault correctly concluding there would be little demand for a rainroof.  Physically large as it had to be, unlike a targa top, the 17's panel was intended (like other hardtops) to be stored in a garage until the warmer months.  One quirk of the R17's nomenclature was in Italy, in deference to the national heptadecaphobia, the car was sold as the R177 but the Italians showed little more interest than the Americans.

Porsche, sunroofs, weight distribution and centres of gravity 

Porsche 917K, Le Mans, 1970.

Porsche in the early 1970s enjoyed great success in sports car racing with their extraordinary 917 but greatly innovation and speed disturb the clipboard-carriers at the Fédération Internationale de l'Automobile (the FIA; the International Automobile Federation) which is international sport's dopiest regulatory body.  Inclined instinctively to ban anything interesting, the FIA outlawed the 917 in sports car racing so Porsche turned its glance to the Can-Am (Canadian-American Challenge Cup) for unlimited displacement (Group 7) sports cars, then dominated by the McLarens powered by big-displacement Chevrolet V8s.  Unable to enlarge the 917's Flat-12 to match the power of the V8s and finding their prototype Flat-16 too bulky, Porsche resorted to forced aspiration and created what came to be known as the "TurboPanzer", a 917 which in qualifying trim took to the tracks with some 1,500 horsepower (HP).  There's since been nothing quite like it and for two years it dominated the Can-Am until the first oil shock in 1973 put an end to the fun.  However, the lessons learned about turbocharging the factory would soon put to good use.

The widow-maker: 1979 Porsche 930 Turbo (RoW (rest of the world (ie Non-NA (North American) market) model) in the “so 1980s” Guards Red with “Sunroof Delete” option.

Although an RoW car, this one has been "federalized" for registration in the US including the then required sealed-beam headlights, fitted inside the "sugar-scoop" housings.  Curiously, although the term “sunroof delete option” is often applied to the relative few 930s with solid metal roofs, there was at the time no such 930 option code and, the sunroof being listed as “standard equipment” on 930s, if a customer requested one not be fitted, what the factory did was not include option 9474 (electric sunroof) on the build sheet.  Later the companion option codes 650 (Sunroof) and 652 (Delete Sunroof) became part of the list for all models.  Rare though it may be in some Porsches, for some the “sunroof delete” thing is surprisingly desirable and in the aftermarket, it's possible to purchase “sunroof delete” panels which convert a sunroof-equipped car into one with a solid metal roof.  They are bought usually by those converting road-going cars for track use, the removal of the 29 lb-odd (13 kg) assembly not only saving weight but also lowering the centre of gravity.

1977 Porsche 930 “Sunroof Coupé” in Talbot Yellow.

Introduced in 1975, the 911 Turbo (930 the internal designation) had been intended purely as a homologation exercise (al la the earlier 911 RS Carrera) so the engine could be used in competition but so popular did it prove it was added to the list as a regular production model and one has been a permanent part of the catalogue almost continuously since.  The additional power and its sometimes sudden arrival meant the early versions were famously twitchy at the limit (and such was the power those limits were easily reached if not long explored), gaining the machine the nickname “widow-maker”.  There was plenty of advice available for drivers, the most useful probably the instruction not to use the same technique when cornering as one might in a front-engined car and a caution that even if one had had a Volkswagen Beetle while a student, that experience might not be enough to prepare one for a Porsche Turbo.  When stresses are extreme, the physics mean the location of small amounts of weight become subject to a multiplier-effect and the advice was those wishing to explore a 930's limits of adhesion should get one with the rare “sunroof delete” option, the lack of the additional weight up there slightly lowering the centre of gravity.  However, even that precaution may only have delayed the inevitable and possibly made the consequences worse, one travelling a little faster before the tail-heavy beast misbehaved.

Porsche 911 Carrera S, Pacific Coast Highway in Santa Monica, Los Angeles, June 2012.

Although it seems improbable, when in 2012 Lindsay Lohan crashed a sunroof-equipped Porsche 911 Carrera, it's not impossible the unfortunate event may have been related to the slight change in the car's centre of gravity when fitted with a sunroof.  She anyway had some bad luck when driving black German cars but clearly Ms Lohan should avoid Porsches with sunroofs.

The interaction of the weight of a 911’s roof (and thus the centre of gravity) and the rearward bias of the weight distribution was not a thing of urban myth or computer simulations.  In the February 1972 edition of the US magazine Car and Driver (C&D), a comparison test was run of the three flavours of the revised 911 (911T, 911E & 911S), using one of each of the available bodies: coupé, targa & sunroof coupé, the latter with the most additional weight in the roof.  What the testers noted in the targa & sunroof-equipped 911s was a greater tendency to twitchiness in corners, something no doubt exacerbated in the sunroof coupé because the sliding panel’s electric motor was installed in the engine bay.  C&D’s conclusion was: “If handling is your goal, it's best to stick with the plain coupe.”  

The Porsche 911 E series and the Ölklappe affair

1971 Porsche 911S (note the flap for the oil filler cap behind the passenger-side door (US market model and thus left-hand drive (LHD)).  The factory confirmed this car was built in July 1971, despite many references to E series production beginning in August.

Although in C&D's 1972 comparison test there was much focus on the rearward weight bias, the three 911s supplied actually had a slightly less tail-heavy weight distribution than either that season's predecessor or successor.  Porsche in 1971 began the build of its E series update (produced between July 1971-July 1972 and generally known as the “1972 models”) of the then almost decade-old 911 and in addition to the increase in the flat-six’s displacement from 2.2 litres (134 cubic inch) to 2.3 (143) (although always referred to as the “2.4”), there were a myriad of changes, some in response to US safety & emissions legislation while others were part of normal product development.  One of latter was the placing of the hinged-flap over the oil filler cap behind the right side door, something necessitated by the dry sump oil tank having been re-located from behind the right rear wheel to in front, one of a number of design changes undertaken to shift the weight distribution forward and improve the handling of the rear-engined machine’s inherently tail-heavy configuration.  In Germany, the addition was known variously as Ölklappe, Oil Klapper or Vierte Tür (fourth door, the fuel filler flap being the third).  Weight reduction (then becoming difficult in the increasingly strict regulatory environment), especially at the rear, was also a design imperative and the early-build E series cars were fitted with an aluminum engine lid and license-plate panel although these components were soon switched to steel because of production difficulties and durability concerns.

Where the troubles began:  The fuel filler flap on the left-front fender (left) and the oil filler flap on the right-rear fender (right).  Apparently, not even the “◀ Oil” sticker in red was sufficient warning.

For the E series 911s, Porsche recommended the use of a multigrade mineral oil (SAE 20W-50 or SAE 15W-40, depending on climate) but were aware those using their vehicles in competition sometimes used a high-viscosity SAE 50 monograde.  With the car’s 10 litre (10.6 US quarts, 8.8 Imperial quarts) oil tank, the fluid’s weight would be between 8.5-9.1 kg (18.7-20.0 lb) and the physics of motion meant that the more rearward the placement of that mass, the greater the effect on the 911’s handling characteristics.  It was thus a useful contribution to what would prove a decades-long quest to tame the behaviour of what, in the early versions, was a car regarded (not wholly unfairly) as handling like “a very fast Volkswagen Beetle” and ultimately the engineers succeeded, it being only at the speeds which should be restricted to race tracks the 911s of the 2020s sometimes reveal the implications of being rear-engined.

VDO instruments in 1971 Porsche 911S.  In home market cars, the oil pressure gauge (to the left of the centrally mounted tachometer) was labelled DRUCK.

However, when in August 1972 the revised F series entered production, the oil tank was back behind the rear wheel and the filler under the engine lid, the retrogressive move taken because there had been instances of gas (petrol) station attendants (they really used to exist) assuming the oil filler flap was the access point for the gas cap and, to be fair, it was in a location used for gas on many front-engined cars (a majority of the passenger-car fleet in most markets where Porsche had a presence).  Quite how often this happened isn’t known but it must have been frequent enough for the story to become part of the 911 legend and the consequences could have been severe and rectification expensive.  The factory paid much attention to oil and also ensured drivers could monitor the status of the critical fluid; all air-cooled 911s ran hot and the more highly tuned the model (in 1971-1972 the 911T, E & S in increasing potency), the hotter they got.  As well as being a lubricant, engine oil functions also as a coolant and the VDO instrumentation included gauges for oil level, oil temperature, and oil pressure; for all three to appear in a road car was unusual but being air-cooled and thus with no conventional fluid coolant, the oil's dynamics were most important.