Fourteen cars you didn’t know were plastic

01st September 2020
Gary Axon

Just over 70 years ago, Californian boat builder Bill Tritt built the Glasspar G2, a sportscar featuring the world’s first ‘production’ automotive body made from a revolutionary new ‘wonder material’: glass reinforced plastic. Also known as GRP or fibreglass, it was discovered accidentally by Owens Corning in the 1930s.


The Glasspar G2 kicked off a fibreglass car body boom, GRP quickly becoming the material of choice for countless low-volume car makers such as Lotus, Alpine, TVR, Matra, Ginetta and more. Some larger mainstream manufacturers were also quick to recognise GRP’s benefits, with Kaiser and Chevrolet revealing fibreglass-bodied prototypes as early as 1952 in the USA, with Saab and Volvo presenting niche fibreglass-bodied sports cars too soon after.

Seventy-years after that first 1949 Glasspar, fibreglass remains the favoured building material for many specialist cars, even if it has now fallen from favour with more mainstream mass-market manufacturers due the subsequent development of alternative hi-tech composites like Kevlar and carbon-fibre. Here are ten surprising GRP-bodied cars produced by mainstream makers better known for using more traditional materials…


Chevrolet Corvette C1 – 1953-62

Chevrolet’s original 1953 Corvette was the first ‘mass-produced’ GRP automobile – just, beating its American rival Kaiser by a matter of weeks. Originally created as a show car for the January 1953 GM Motorama display at the New York Waldorf Astoria, the GRP Corvette EX-122 concept generated enough interest to convince General Motors (GM) to commence production just six months later. GM's celebrated designer Harley Earl chose fibreglass as it was lightweight, rust-proof, and offered an economical way to produce the Corvette without the expense of large sheet metal pressings. 

The Corvette was produced using conventional fibreglass construction methods until the third generation C3 in 1968, when a press-mould process was introduced to simplify and decrease the GRP’s production time, this advance leading to the development of SMC (sheet moulded compound), used for all 1973-2004 Corvette body panels. Post-2004, Corvettes have continued to use SMC, but with a higher carbon-fibre content for strength and weight advantages.


BMW M1 – 1978-81

In its bid to break domestic competitor Porsche’s late-1970s dominance of Group 5 racing, BMW developed the M1. The Bavarian marque’s first true GRP-bodied car, as well as its first mid-engined supercar – initially developed with Lamborghini’s assistance – it was the first machine born out of the new Motorsport division, the creator of BMW’s subsequent athletic ‘M’ models. 

Conceived primarily for competition use, the Ital Design-styled (and built) M1 used riveted GRP panels, attached to a lightweight but rigid steel spaceframe chassis.

The M1 debuted BMW’s lauded M88 277PS 3.5-litre straight-six motor. With an efficient 1,300kg package achieving a 161 mph top speed, on paper the M1 promised much. Unforeseen Group 5 race regulations changes, compounded by delays with the Italian-developed tubular chassis, an overly-complex production process and an ambitious £37,500 price tag (the contemporary flat-12, 371PS, Ferrari BB 512 costing £35,000) saw just 399 M1 road cars built, with around 55 ‘Formula 1 side-show’ Procars and endurance racers also made.

A decade after the M1, BMW went on to launch its second plastic car; the Z1 roadster, which featured removable GE’s Xenoy thermoplastic bodywork for the side panels and unusual retractable doors, with GRP bonnet, boot, and tonneau cover.


Ford RS200 – 1985-86

You have to feel for the unfortunate Ford RS200, a fibreglass-bodied homologation special developed to compete with Peugeot, Lancia and MG in Group B rallying, but killed off before the model had chance to really prove itself.

Ford’s first (and only) rally of the 1986 season saw an RS200 involved in a tragic incident that took three spectators lives on the Rally de Portugal. This Portuguese accident was one of many that signalled Group B as simply too fast and dangerous, the Formula being outlawed at the end of 1986.

This left Ford with a problem. Due to Group B’s cancellation, the RS200’s competition career was suddenly over, causing some RS200 buyers to refuse delivery of the cars. As a result, Ford never made the full 200 quota of Reliant-built road-going RS200s required to comply with homologation regulations, with reportedly 158 examples made between October 1985 and January 1986. Ford apparently stripped down 50 road-legal RS200s already built to resell them with extra equipment fitted, with others dismantled for spares and unsold competition cars rebuilt as road cars and sold off at advantageous prices.

The RS200’s GRP coachwork was styled by Ghia and assembled around a honeycombed aluminium, steel and carbon-fibre central tub, into which a Cosworth-developed 1.8-litre turbocharged four-cylinder motor was centrally-mounted.

The bodywork of most of the RS200’s mid-engined Ford GT40 and GT70 competition predecessors were also made of fibreglass, as was the special pick-up flat-bed of Ford’s Transit 2 Flareside, which like the RS200, was constructed at Reliant’s Tamworth factory alongside its three-wheeled Rialtos!


Autobianchi Stellina – 1963-65

Autobianchi’s youthful Stellina was a two-seater barchetta with glass-fibre bodywork; not only a first for the Fiat Group, but also for any Italian car. Previewed at the 1963 Turin Salon, the definitive GRP Stellina was launched in 1964, designed by engineer Luigi Fabio Rapi (father of Autobianchi’s Bianchina) with some styling support from Tom Tjaarda.

The Stellina’s polyester resin and fibreglass body was remarkably robust, losing some of GRP’s lightness advantages in the process due to Italians being sceptical about the quality and durability of plastic materials in period; a standard ‘easy repair’ coachwork kit being provided to publicise the body's resistance to corrosion.

The body was fixed onto a box-type frame structure in welded sheet metal, taken from the popular Fiat 600 D, along with its 30PS, 767cc motor, giving a pedestrian 71mph top speed. An improved second series Stellina adopting a marginally more powerful 781cc Fiat engine to reach 78mph. Autobianchi asked a hefty 980,000 Lire for the Stellina, resulting in just 502 examples being built during a short two-year production run, with around 150 exported. The model’s fate was ultimately sealed by the debut of the prettier, cheaper Fiat 850 Spider in 1965.


Mazda Autozam AZ-1 – 1992-94

Just ahead of the early 1990s Japanese economic crash, Mazda, then Japan’s fourth largest car maker, was on a roll, optimistically launching four new car brands: Autozam, Efini, Eunos, plus the stillborn luxury Amati. Each targeted different sectors of the home new car market.

Autozam was (briefly) Mazda’s domestic small vehicle marque, its stand-alone dealers selling kei and niche cars, including imported Lancia models! Having begun its career as the Mazda-branded AZ-550 in three differing concept bodystyles at the 1989 Tokyo Show, by 1992 this tiny plastic sports car reached production as the Autozam AZ-1, launched just after the Japanese economic bubble had burst.

With a Suzuki-sourced three-cylinder, 657cc turbocharged motor with 64PS mounted mid-ships in a steel chassis, the miniscule Autozam featured a Group C-inspired plastic bodyshell with a glass gullwing canopy. Priced too close to Mazda’s larger and more practical MX-5, and substantially higher than its sporting Honda Beat and Suzuki Cappuccino kei-car rivals, the costly AZ-1 never reached its planned 800 monthly sales, with production soon suspended.   

The lowest Japanese car ever made, the AZ-1 wasn’t just Mazda’s first and only plastic (and mid-engined) production car to-date, it was Suzuki’s too. The result of a joint venture between the two companies, the latter sold as the Cara and accounted for just 531 (12 per cent) of the total 4,392 gullwing coupes, all built by Suzuki.


Citroën Bijou – 1959-64

Encouraged by success since Citroën commenced UK production in Slough in 1925, from 1954 Citroën GB began the local assembly of 2CVs, tailoring the rustic model closer to British tastes with plusher upholstery, chrome bumpers and so on.

The unconventional 2CV failed to find favour first time around with conservative Brits though, so to use up spare 2CV chassis and engines, the unique-to-Slough Bijou was launched at the 1959 Earls Court Motor Show to appeal more strongly to local sensibilities.

Penned by the designer of the innovative GRP monocoque Lotus Elite – Peter Kirwin-Taylor – the 425cc Bijou wore a modern Whitson & Co.-moulded fibreglass bodyshell, styled with a family resemblance to the innovative DS and using some components taken from Citroën’s halo model, such as its single-spoke steering wheel and Smiths instrumentation.

The Bijou shared its Earls Court debut with the BMC Mini, Ford Anglia and Triumph Herald, this strong British trio instantly killing off the costlier (£674) Citroën’s chances of success. The Bijou enjoyed a superior ride quality over its three new rivals, but with lethargic performance, marred by its good quality but weighty GRP bodywork (making it heavier than a steel 2CV!), just 211 Bijous were built.


Ferrari 308 GTB ‘Vetroresina’ – 1975-77

Whilst not traditionally considered a ‘mainstream’ make, Ferrari is an automotive colossus against a myriad of minor GRP sportscar marques; Fairthorpe, Gordon-Keeble, Jide, Elva, and so on.

The holy grail for Ferrari 308 admirers, the early GTB vetroresina is included here for its uncommon Scaglietti-made fibreglass coachwork, with just 808 GRP Berlinettes built before Ferrari switched production to ‘regular’ steel in 1977. The svelte GRP GTB was Ferrari’s rapid response to the muted reaction the Bertone-designed Dino 308 GT4 2+2 received at its 1973 introduction as an indirect but underwhelming successor to Pininfarina’s celebrated Dino 246.

With many Ferrari customers rejecting the 308 GT4, they wanted to get their driving gloves on the new 308 GTB immediately; fibreglass proving an expeditious method of getting the new mid-engined coupes delivered to buyers quickly. The Ferrari’s ripple-free GRP was to a high quality standard, but in contrast to steel and alloy, it felt down market and deterred some customers with complaints of squeaks and creaks. GRP 308s offered key benefits too though, being immune to rust – unlike later non-galvanised pre-1983 models – with a useful 150kg weight saving, a dry-sump lubrication system producing around 10PS more than steel-bodied GTBs, plus scarcity.


Daimler SP250 ‘Dart’ – 1959-64

Britain’s first car maker Daimler had long nurtured its deserved reputation as one of the Country’s most respected, dignified but frightfully traditional vehicle producers. Needing to revive its fortunes and staid image, Daimler shocked all by unveiled a daring fibreglass-bodied V8 sports car at the 1959 New York Show.

Initially named Dart, Daimler’s new sportster featured four-wheel disc brakes and an Edward Turner-designed 2.5-litre, 142PS compact V8 engine, wrapped-up in distinctive of-the-moment GRP bodywork, designed by Percy McNally and Jack Wichers. Redesignated SP250 when production began, Daimler launched the model too prematurely with numerous unresolved rough edges evident, serious chassis flex being the biggest issue.

In 1960 Jaguar bought ailing Daimler and quickly set about rectifying the SP250’s shortcomings, adding extra outriggers to improve rigidity and strengthening the hoop between the A-pillars to create the 1961 B-Spec model. With its own new E-type set for its sensational debut, Jaguar was understandably reluctant to invest more in its now in-house rival SP250, with only minor detail improvements made until production ended in 1964, just 2,645 examples later (26 being built for the Metropolitan Police).

With unresolved styling (which Hooper and Ogle both attempted to remedy, the latter leading to the Reliant Scimitar GT coupe) and costly production methods, the SP250 never achieved Daimler’s expectations, although its legacy lived-on with Turner’s excellent V8 shoe-horned into the Jaguar MK 2 bodyshell to create the stronger-selling Daimler 2.5 V8.


Saab 97 Sonett II/III – 1966-74

In 1956 Swedish aircraft-cum-car maker Saab combined advanced fibreglass and aviation alloys for its 94 Sonett prototype, a roadster created to successfully set multiple speed records for its small two-stroke engine displacement class. Six front-drive 94 Sonetts were built, two survivors now residing in Trollhattan’s Saab Museum.

A decade later, Saab revived the Sonett name for its first true GRP-production sports car, the two-seater ‘97’ coupe. This new 1966 Sonett II was based around a modified MFI13, a two-stroke Saab 96 Monte Carlo-based sports prototype created by fibreglass specialists Malmö Flygindustri and put into low-volume production at ASJ in Arlöv.

Aimed squarely at the lucrative US market, after 258 two-stroke 841cc examples, the Sonett II’s 71PS engine was switched to Ford Taunus V4 power for 1968 to meet tougher American emission requirements. Having established a small but enthusiastic US following, the front-drive Sonett II was superseded in 1970 by the restyled Sonett III, using the same Ford V4 power and Sonett II’s central hub, but with a sharper Sergio Coggiola-designed wedged profile.

The GRP Sonett III proved as nimble and entertaining to drive as its predecessor, but its American sports car market sales impact remained marginal; a total of 10,219 Sonetts built before being dropped in late 1974.

As an aside, the sporting Saab’s unusual name was not a mis-spelling of a sonnet (double n, one t) fourteen-line poem, but rather an abbreviation of the Swedish phrase så nätt den är , translated as ‘it's so neat.’ Despite its Swedish name though, the Sonett was only sold intermittently in its home market, for the 1968 and 1972 model years.


Studebaker Avanti – 1962-63

By early 1961 the once robust Studebaker was struggling and in urgent need of reviving its fortunes. Step forward Studebaker’s ambitious new president, Sherwood Egbert, tasked with swiftly rejuvenating the marque’s image and income.

Within weeks of taking the wheel, during a flight Egbert scribbled the lines of an image-changing GT to tackle the Corvette. Once landed, he contacted his celebrated industrial designer friend Raymond Loewy to share his GT vision to pull Studebaker from the brink. Loewy quickly assembled a small talented team at his Palm Beach villa to work on the new Studebaker concept; a 1:8-scale proposal presented to (and approved by) Egbert within a month.

Loewy’s Studebaker was a refreshingly modern and uncluttered coupe, unlike any contemporary American car. Within 12 months, Studebaker’s brand-new Avanti was revealed to instant acclaim at the 1962 New York Auto Show. Strikingly clad in futuristic fibreglass coachwork, the new Avanti had the desired effect, Studebaker’s dealers being inundated with orders for the 4.7-litre V8 GT. The Avanti’s GRP body production was outsourced to a Corvette panel-making Ohio supplier that struggled to keep pace with demand, forcing Studebaker to pull bodywork manufacture in-house.

Frustratingly this was too little, too late, Studebaker increasingly exceeding its promised delivery times, resulting in many customers cancelling their Avanti orders. Days before Christmas 1963, penniless Studebaker was forced to close its South Bend, Indiana, factory, with less than 4,650 Avantis produced in 18-months.  

Proving too good to die young, two ex-Studebaker dealers restarted Avanti production in 1965. Re-branded Avant II, South Bend production continued largely true to Loewy’s original design (with a few gaps) until 2005, with 3,473 Avanti II coupes made.


Volvo P1900 – 1956-57

With its dependable but dull reputation, in the early 1950s Volvo attempted to spice-up its image, injecting some excitement into its key new North American export markets in 1954 with an open sports car prototype, fitted with fibreglass-reinforced polyester body, created by Glasspar’s GRP-pioneer Bill Tritt.

Called P1900, the one-off Volvo stirred much interest, prompting limited production from 1956. A raft of GRP-build quality problems and weak performance though saw production wound up by 1957, with just 67 Volvo PV444-based P1900s built, most examples being sold in chilly Sweden!


BMC Mini – 1969

Strong global demand saw BMC commence worldwide Mini production in the 1960s, the innovative car adapted to local market needs; from Italy to Australia.

The small South American market of Chile wanted the Mini but imported cars were banned. BMC could not justify the tooling and equipment needed for Chile to produce steel bodies, so it turned to experienced Isle of Man GRP specialists Peel Industries (of P50 microcar fame) to develop a fibreglass Mini (plus a BMC ‘ADO16’ 1100) bodyshell, with local production beginning in 1969. Another South American country, Venezuela, later revived the GRP Mini in 1992, sold as the Cord, and building 768 examples.


Singer SMX – 1953

Prior to its takeover by the Rootes Group, Coventry-based Singer was a surprising GRP ‘early adopter’, using a fibreglass bonnet and other panels for its facelifted SM1500 – renamed Hunter – in 1954.

This followed Singer’s earlier 1953 build of ten GRP SMX roadster prototypes. The slab-sided SMX was intended as Singer’s replacement for its aging 9 Roadster, with lower-cost GRP used at the recommendation of its US distributor Bill Vaughan, who had already built a one-off Singer-based special using a pioneering Glasspar G2 fibreglass bodyshell.

ICI’s subsidiary Marston-Excelsior moulded Singer’s GRP panels to a poor quality standard; Singer soon dropping the material ahead of its Rootes Group takeover.


Lancia Stratos – 1973-78

Undeterred by its earlier fibreglass Autobianchi Stellina experience, Fiat returned to the material for the striking Stratos’ bodywork, its Lancia division’s purpose-built rally weapon of 1973.

With dramatic Bertone-styling (first revealed in prototype form in 1971), the Stratos utilised GRP lift-up front and rear sections, wrapped around a dart-shaped central fibreglass cockpit.

The Stratos scored a World Rally Championship hattrick from 1974-76, the firesome Lancia often victorious sans its huge clamp-down rear GRP bodywork, which was heavy and prone to becoming dislodged. Using the acclaimed mid-mounted Dino 2.2-litre V6, Bertone assembled 492 road-going Lancias to (almost) satisfy homologation rules.

BMC image by Vauxford, Singer image by Rick Feibusch.

  • Chevrolet

  • Corvette

  • Lancia

  • Stratos

  • BMW

  • M1

  • Ford

  • RS200

  • Autobianchi

  • Mazda

  • Citroen

  • Ferrari

  • Daimler

  • Saab

  • Studebaker

  • Volvo

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