Concepts and Prototypes : Hillman Avenger Liftback (R424)

The 1970 Hillman Avenger Liftback was the Rootes Group’s attempt to extend the appeal of its new mid-sized saloon – with a smaller hatchback version.

The project would originally go nowhere, a casualty of model rationalisation plans. However, it was revived in 1975 to become what would eventually be known as the Chrysler Sunbeam. New sketches reveal how the transformation was made possible.

Hatching out a new Avenger for the 1970s

Project R424 sketches by David Evans

In 1970, with the launch of the Hillman Avenger in two- and four-door saloon form, as well as five-door estate, it looked like Rootes-Chrysler had a ready-made range of cars to go head-to-head with Ford in the UK and Europe. The Chrysler B Car, as it was known, was an ambitious project, which cost the company lots in development resources being, effectively, an all-new car from the ground up.

Interestingly, the range described above was far from complete. We already know about the Ford Capri and British Leyland’s Morris Marina-based Project Condor-rivalling Chrysler R429 Coupe. This car would have built on the Avenger’s undoubted good looks and excellent drivetrain by adding a serious dose of sex appeal, and hopefully gone on to sell at a handsome profit. However, even before the Avenger was launched in the UK, parent company Chrysler was feeling the pinch, so reduced its spending and canned the project before it made it into production. More’s the pity…

But as well as the Coupe, there was also a shorter Avenger in development, known as the Liftback – in 1970, when the project was well underway, this new smaller model (which was still rear-wheel drive) was being conceived for the urban smart set that wanted practicality in a city-friendly package.

Hillman Avenger Liftback

So, what was the Hillman Avenger Liftback?

According to Chrysler UK expert Graham Ariss, the Liftback was conceived early in the Avenger’s development programme. ‘Before Chrysler pulled the plug on the UK investment in the early 1970s, there were plans that the Avenger would spin off a whole range of variants,’ he said. ‘Included in this interesting lineup was the compact Liftback variant, which would retain the front of the Avenger, but have a cut short liftback tail.’

Chrysler clearly wanted to make the most of its extensive investment in the Avenger, and this seemed like a logical extension of the range that could have been an early winner in the fledgling supermini market. ‘If you look at the Sunbeam pages on this site, you can see one of the styling proposals (top) was released in the launch brochure for the Chrysler Sunbeam, which is essentially a facelifted Avenger hatchback,’ he added.

Initially, the project didn’t get very far. ‘That was the original intention of the Avenger Liftback. It was proposed as an Avenger spin-off variant before investment from Chrysler was cut in the early 1970s,’ Graham added. That is not to say that this abandoned hatchback project wouldn’t see the light of day long before we gave it an airing on AROnline.

The work didn’t go waste, though

Project R424 sketches by David Evans

Project R424 sketches by David Evans

Project R424 sketches by David Evans
Chrysler UK (and later Land Rover) Stylist, David Evans, was drafted in to update the Hillman Avenger Liftback into a supermini challenger of the late 1970s – while also using as many carry-over parts as possible

From Avenger Liftback to Chrysler Sunbeam

Chrysler UK hit trouble in 1975, and ended up being bailed out by the UK Government, on the understanding that it would be able to produce a new supermini in order to improve its competitiveness. So, at the end of 1975, the Hillman Avenger Liftback was dusted off by the Whitley Design Team to become Project R424.

The design took shape under the leadership of Roy Axe, who’s team penned a new body for this older design. One of the Stylists was David Evans, who would end up becoming a design leader for Land Rover via a posting at Simca in Poissy – his sketches can be seen above. They used a variety of carry-over parts from the Avenger.

This is one of the main reasons why Chrysler UK was able to get the Sunbeam into production in such a short space of time. It was because they had already done the preliminary work years before on the Avenger Liftback, so used this as a starting point.

However, as Graham noted, the R424 shared rather a lot with its earlier forebear. ‘The Sunbeam used a lot of Avenger pressings, including the two-door version’s door skins, but featured all-new glass with a different windscreen angle and a larger glass area – when compared to the Avenger, the Sunbeam had a light and modern interior. The Sunbeam therefore ended up fitting neatly into the range alongside the upcoming front-wheel-drive Chrysler Horizon.’

1977 Chrysler Sunbeam
1977 Chrysler Sunbeam ti
Keith Adams


  1. Looking beyond Chrysler’s financial problems and what was potentially available. It is interesting to note US Chevrolet Chevette versions of the Vauxhall Chevette featured both 3/5-door hatchback variants, is it known whether the Avenger Liftback later the Sunbeam had a similar potential?

    Would it be correct to assume the Avenger Liftback and Chrysler Sunbeam share roughly similar dimensions (in which case there is further room at the lower end of the range for the likes of the Mini-rivaling Simca 1000-replacing Simca 936 and Supermini-sized C2-Short projects)?

    Seem to recall in past threads of the Avenger Liftback being intended to indirectly replace the Imp and utilize a 1100cc version of the Avenger engine (not sure whether it would have carried over the Imp-derived 928cc engine as was the case on the Sunbeam even if there was room in retrospect within the design for an extra 20cc via George Mowat-Brown’s Imp book).

    Also recall mention being made of the Avenger or at least Chrysler UK’s Avenger estate-derived proposal for what became the Chrysler Alpine being converted to FWD, which brings to mind the question of whether a FWD conversion could have filtered down to the Avenger and Avenger Liftback replacements (if they possessed similar scope) as a low-cost rebody (e.g. Sunbeam but FWD) to further increase the longevity of the platform into the 1980s before finally being replaced?

    That said a full FWD conversion of all the Avenger variants would have potentially denied us the Lotus Sunbeam (short of the Lotus engine being detuned by about 20 hp), unless the Avenger engine could form the basis of a more than adequate (non-BRM) alternative whether in Vizard-tuned 130 hp 1.6 NA / 150 hp 1.6 “Turbo Tiger” or 105+ hp 1.8-2.0 forms.

    • I understand both went down the same route of cutting out around 3 inch from the wheelbase of the Avenger making it 95 inch, to be honest, I think they should have kept it at 98 inch, I doubt it would have matter much outside but it would have helped inside.

      With the Horizon already signed off, there was no point in developing a five door variant.

      Imp engine cost a lot more to make that the Avengers all iron engine, not only due to its complexity, but because it was cast in Linwood, shipped to Stoke in Coventry for machining and assembly before returning to Linwood to go into the back of an Imp. This amazingly expensive engine the being sold in the UK’s cheapest car. As a result Chrysler’s executives wished for the day they could kill it and the Imp.

      The plan was that with when the Premium car (what became the 160/180/2 Litre) arrived in 71 and replaced the Arrow, the now debugged Avenger would go North to Linwood where the two Linwood tracks would release capacity for additional derivatives (Ryton at the time was working 24 hrs triple shift to keep up with demand). The Linwood foundry would be kept busy casting all the aluminium gearbox casings needed for all the Avengers they would be making.

      Chrysler Europe in the mid 70s, did not, nor ever would have had the funding to develop a new fwd small car. The plan was instead to go down the Peugeot 104 route with the Horizon and do a short two door version, this would have utilised the Simca 1000 engine as its base power unit.

      The FWD development of the Sunbeam is a theoretical possibility, but has to be seen in the context that the FWD proposal for the evolution of the Avenger estate was a last ditch attempt to keep the engineering of the car in the UK. The reality was that as Chrysler US has no interest in the car, there was never going to be money for anything but the cheapest option in Chrysler Europe, and so the Simca route to FWD was always going to win through.

      The original and fwd Alpine proposals (and in truth Simca) for the Alpine all pointed to them returning their brands with the car to a more premium market segment and so proposals were for twin cam engines in line with what you found under the bonnet of a Lancia or Alfa Romeo. The Lancia Beta was seen by both Uk and France, what the Alpine should have been, a cynic might thus point out that whilst they never offered something close to its driving experience, they did a reasonable impression of its ability to turn to dust on the drive.

      • Know the Simca 936 project was conceived in the mid-1960s, though otherwise unsure to what extent the prototype was a downscaled Simca 1100 yet could have also potentially replaced both the Simca 1000 and Hillman Imp.

        Exploring the original intention of what became the North American L-Body Horizon (itself forming the basis of the K platform family) being sold in Europe in place of the 1100/Alpine-based European Horizon, could the platform have been downsized even further to spawn an alternate (or even a later replacement for the) C2-Short? IIRC it was mentioned elsewhere the Northern American Horizon was in essence a reverse-engined Golf platform, with the mk2 Golf platform itself going on to later underpin both the mk3 Polo and even smaller Lupo (plus other related variants) until the mid-2000s.

        Wonder how Chrysler Europe would have hypothetically adapted the K platform to the European market (and turned it into something more competitive against European rivals) had the opportunity been available as well as the Omni / North American Horizon replacing P platform e.g. the Dodge Shadow (prior to the Neon), the latter curiously appears to loosely resemble the Talbot Arizona / Project C28 in some respects minus the Peugeot/PSA contribution and larger dimensions. Would it be correct to assume the original intention for C28 pre-PSA takeover was for the project to utilize part or all of the North American Horizon (or give one last rebody / hurrah to the European Horizon)?

        In the right environment a Chrysler Europe version of the L/K platform (plus other variants) from a Supermini (plus possibly City Car) up to a large car / minivan could have helped it up to the mid-1990s. Not sure how accurate the following is though there was a suggestion much of the Peugeot 309 eventually found its way into the Peugeot 306 and Citroen ZX/Xsara, with some going as far as to say the Peugeot 309 was to the Peugeot 306 and Citroen ZX/Xsara what the Citroen AX became to the Peugeot 106 / Citroen Saxo.

        The last curiosity as far as Chrysler superminis are concerned would have to be the Tritec-powered 1999 Chrysler Java concept, which almost appears to share some relation to the 2002 Mitsubishi Colt and 2004 Smart Forfour. While Chrysler Europe would have probably taken a different approach to the Neon (that itself was said to be loosely related to the L – Omni / P – Shadow platforms), one can almost see how a surviving / thriving Chrysler Europe would have evolved in better circumstances up to the 1990s to early-2000s without much involvement from Mitsubishi or PSA (aside from possibly using the TUD/XUD, DJ/DK and HDi diesel engines).

        • The Simca 936 was very much a scaled down 1100, they were both conceived at the same time and adopted the same solutions, but beyond sharing the same base power unit, the 936 being Mini sized precluded any component sharing.

          As I understand it, having struggled with their owners in Detroit to get the Simca 1100 signed off, they knew they would not get financing for something even more compact so never offered up for consideration for production.

          The Horizon had funny evolution, it was originally conceived as a Simca 1100 replacement by re-skinning the Alpine underpinnings that had themselves been taken from and revised from the 1100. It is important to note that like the Simca 1100, it was always going to be half a size bigger than the original Mk1 Golf so it was not where you wanted to start with for a super mini.

          However in Detroit, the fuel crisis meant they were desperate for a compact car to fend off the likes of the Rabbit (Golf) and so they turned to their European operation.

          This changed the economics of the project, with the number of units Detroit were planning on building, the economy of assembling strut front and torsion beam rear over the savings of sticking with the Simca more complex but already tooled up platform won through. It was then intended that car would proceed with a all new platform on both sides of the Atlantic.

          However very late in the day, a cost saving exercise in Europe, pushed through the reversion to the existing running gear. This is why the seating position seems strange (and unlike the Alpine,1100 and the US version) with the steering wheel very low compared with the seat height. This is because the floor was raised to accommodate the torsion bars for the front suspension, yet budget constraints did not allow a revised steering wheel position to be engineered for the European version.

          So the shortened Horizon, which was a European project would without a doubt stuck with the Simca running gear, it would not have been cost effective to revert that design back again to the US platform.

          I don’t see any reason why the US platform would not have worked with revised settings in Europe, in the same way the Golf etc with similar set up worked both sides of the Atlantic.

          The C28 was a project conceived at Whitley after the Peugeot takeover and from day one looked to utilise the Peugeot parts bin, so its starting from too different a place to imagine what it would have evolved into had Chrysler Europe still existed.

          However given that the shortened 2 door Horizon that would have replaced the Sunbeam and the front suspension for what became the Tagora were conceived around using existing Horison / Alpine suspension components, it seems like they were stuck with the Simca oily bits for the foreseeable future.

          However I know (and saw) that Whitley were in those last days of Chrysler were evaluating Mitsubishi Mirage and Colt (and were I understand very impressed by them), so it is possible they would have done a BL/Rover and adopted light re-skins of Japanese products for Europe.

    • The US Chevette 5 door had a longer wheelbase than the 3 door. There wasn’t necessarily much particular demand for a 5 door hatch; it was the easiest way to get a 4 door into production and the US Chevette’s image was established in the market as a hatch. The 5 door definitely lost whatever sporty appeal the 3 door had.

      • Was aware of the increased wheelbase on the 5-door Chevrolet Chevette, done after the Vega was discontinued. The US had a rather indifferent attitude towards its smaller cars during the 1970s then in the rest of the world.

        Can understand the rationale of the 3-door Chevette and Avenger Liftback/Sunbeam acting as temporary contenders in the Supermini class until new replacements are developed, with the latter intended to replace the Imp.

        Yet not convinced by the Avenger Liftback/Sunbeam being developed as an Imp-replacing Supermini and thus requiring a reduced wheelbase as well as carry over of the Imp-based 928cc unit. When retaining the wheelbase and allowing the Sunbeam styling to be applied as an Avenger rebody with more body-styles and low-end 1100 Avenger engine seems to be more cost effective option for Chrysler UK.

        Even though Roy Axe looked at a fastback based on an Avenger Estate-platform as a Chrysler UK proposal for what became the Simca Alpine, perhaps that enthusiasm for the fastback at the period could have instead been better applied on an Avenger fastback hatchback rather than a C6 idea, unless Chrysler Europe is in a position to develop a saloon body-style from the Horizon (and C2-Short Supermini in lieu of the Avenger Liftback/Sunbeam).

        • Mean the last part in the context of the Horizon platform being used to directly replace both the Avenger saloon and Imp.

          • While the Vega name was discontinued (it was radioactive), most of the Vega models continued in the Monza series in a Marina/Ital transformation.

          • There was a strange overlap of the C-Segment and D-Segment class cars in North America at the time. When it came to wheelbase the 5-door Chevette was similar to the discontinued Vega, even though the Vega family in general was comparable to the Viva HC & Mk1 Cavalier / Ascona A-B.

  2. As then part of the CUK (Chrysler UK), field sales team, we were based in offices at the Linwood production plant.

    I did once see parked out-the-back, what would probably be best described as a “shopping wagon”, something the production people used for their own internal transport around the facility ( . . . We didn’t have “facilities” in the 1970s!! . . . . It was a “factory”!!).

    Pretty certain now, that this was an Avenger ESTATE body (NOT a four-door saloon), with the more modern, angular, SUNBEAM front end.

    I would imagine this was produced as a “whimsy” of the production hierarchy, rather than as a formal request from the styling/design team at Whitley.

    It did show that the Avenger could be given an inexpensive “facelift”, but only at the cost/risk, of detracting from the individual personality of the “new generation” more modern, angular, SUNBEAM, Alpine, and Horizon.

    It was NOT – however – a four door/estate derivative of the SUNBEAM. The (more rounded) side pressings, shallow glass area, were all previous generation Avenger.

  3. At Whitley as a pool car for a while, they had a Sunbeam with which must have been modified Avenger front doors and a Simca 1100 box van on the back (I guessed resized as needed).

  4. The Sunbeam was a masterstroke of ailing Chrysler Europe, as it was merely a shortened Avenger with a liftback and the same technology.OK it never seriously challenged the Ford Fiesta, and European sales were small, but the Sunbeam was a viable rival to the Chevette hatch and came with a large choice of engines and trim levels. Also while it was a bruiser with high fuel consumption, the Lotus Sunbeam could outrun a Golf GTi easily and was an excellent rally car.

  5. The second of the 3 David Evans illustrations is quite coupe like, and indeed reminds me of the Renault 15.

  6. The first proposal immediately reminded me of a Vauxhall Chevette, and the last proposal – with the abrupt tail – made me think of Citroen LN.

  7. I still think the Chevette was better looking than the Avenger liftback concept. At the time the Chrysler Sunbeam never appealed to me either though in hindsight it now doesn’t look so bad.

  8. The Sunbeam was quite a good looking car and sold in decent numbers during its four year lifespan. It wasn’t the best car in its class, as the rwd transmission tunnel robbed passenger space and the 928cc version was a sluggard, but the bigger engined cars went well, the Sunbeam had two well liked performance versions, and equipment levels were decent. I’d say Chrysler cobbled together a competitive car on a limited budget and did OK.

  9. A rallying acquaintance had a Sunvenger, it was a Sunbeam 1600 with the front wings, bonnet and front panel replaced by Avenger parts. Reason being that he pranged it and found replacement Avenger panels were significantly cheaper than Sunbeam ones.

  10. I think the Avenger was a decent enough car, being a regular top ten best seller in the seventies, and its Sunbeam offspring a clever attempt to create a supermini on a shoestring. Both cars were using ageing technology by the time the Sunbeam came out, but buyers who wanted an honest, all British car that wasn’t a gamble like a Leyland product would probably be paying the Chrysler showroom a visit. Actually the Chrysler era Avengers did look quite stylish from the outside, with a Cortinaesque front end, and looked quite swish with a vinyl roof and front foglights.

  11. Considering the Chevette was still into production until 1984 with similar underpinnings shows Chrysler weren’t too far off the mark. The Toyota Starlet & Mazda 323 were also RWD superminis.

  12. @ Richardpd, the Chevette was another car that used a totally new body with mechanicals from an older car( the Viva). It looked modern and funky compared to the Viva and was a good car to drive and cheap to run, and became an instant hit for Vauxhall. The Chevette probably used rwd as it was cheaper than developing a fwd car and many buyers were still reluctant to embrace fwd, considering the big sales for the Escort and Viva at the time. Later on, the Chevette kept sales healthy by offering saloon and estate alternatives and being a cheaper alternative to the fwd Astra.

    • Simplifying things, the Chevette was basically an Opel Kadett B with a new nose and an HC Vica 1256cc engine and gearbox.

      • The Chevette, like the Sunbeam, was a response to a growing market for three door cars and using the Opel body and the Viva drivetrain must have saved tens of millions in development costs. While not in the same dire financial situation as Chrysler, Vauxhall had been suffering from falling sales and a confused model range. The Chevette and the Opel based Cavalier proved to be the saviours of Vauxhall, who saw a healthy increase in sales and had two genuinely good cars to sell.

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