The Caterham 7 (or Caterham Seven) is a super-lightweight sports car produced by Caterham Cars in the United Kingdom. It is based on the Lotus Seven, a lightweight sports car sold in kit and factory-built form by Lotus Cars, from 1957 to 1972.
After Lotus ended production of the Lotus Seven, Caterham bought the rights to the design, and today make both kits and fully assembled cars. The modern Caterham Seven is based on the Series 3 Lotus Seven, though developed to the point that no part is the same as on the original Lotus.
Various other manufacturers offer a sports car in a similar basic configuration, but Caterham owns various legal rights to the Lotus Seven design and name. The company has taken legal action in the past in order to protect those rights, although in South Africa, it lost its case against Birkin on the basis that it never obtained the claimed rights from Lotus.
History Colin Chapman had been a Royal Air Force pilot, studied structural engineering, and went on to become a innovator in motorsports design. He founded Lotus Engineering Ltd. His expertise on light, powerful cars and performance suspensions guided much of his development work with the basic design philosophy of, "Simplify, then add lightness". His Lotus 7 had its debut at the 1957 Earl's Court Motor Show in London. They were priced at £1,036 including purchase tax but it cost £536 in kit form as no purchase tax was required. It weighed . Fast and responsive, the Lotus 7 was one of Chapman's masterworks, an advanced machine that surpassed the earlier Lotus 6 as a vehicle that could perform well on the track and be driven legally on the road.
In 1973, Lotus decided to shed its kit car image and concentrate on limited series motor racing cars and up-market sports cars. As part of this plan, it sold the rights to the Seven to its only remaining agents, Caterham Cars in England and Steel Brothers Limited in New Zealand. At the time the current production car was the Series 4, but when Caterham ran out of the Lotus Series 4 kits in 1974 they introduced its own version of the Series 3, as the Caterham Seven. The modern-day Road sports and Superlights (in "narrow-bodied chassis" form) are the direct descendants of this car and therefore of the original Lotus 7.
Chassis and suspension
As with the Lotus Mark VI before it, the original Lotus Seven used an extremely light space-frame chassis with stressed aluminium body panels. Although the chassis has had numerous modifications to strengthen it and accommodate the various engine and suspension setups (and to try to find more cockpit space for the occupants), this basic formula has remained essentially the same throughout the Seven's life (with the exception of the Series 4, which used steel for the cockpit and engine bay and glassfibre for the bodywork). Early cars used a live rear axle, initially from various Fords, later from the Morris Ital. De Dion rear suspension was introduced in the mid-1980s and both geometries were on offer until 2002 when the live-axle option was phased out (though later reintroduced for the 160/165 and 170/Super Seven 600 versions). Late 90s and early 2000s versions (such as the Superlight) employed adjustable double-wishbone suspension with front anti-roll bar and a de-Dion rear axle, located by an A-frame and Watt's linkage.
The Caterham 7 range was based exclusively on this Series 3 chassis until 2000, when the SV (Series V, or Special Vehicle) chassis was released, aimed at accommodating the increasing number of prospective buyers who could not fit comfortably in the Series 3 cockpit. The SV chassis offers an extra of width across the cockpit, at a cost of of extra weight, and both chassis sizes are available today in earlier Superlight and current 360, 420, 620 and Super Seven 2000 configurations, though only the S3 chassis is offered on the 170 and Super Seven 600.
The SV chassis subsequently provided the basic dimensions for the Caterham CSR. The suspension was completely redesigned, bringing the front suspension inboard, using pushrods, and replacing the De-Dion rear axle with a lighter, fully independent, double-wishbone layout with new coil/damper units. Additional chassis modifications resulted in a 25% increase in torsional stiffness. The CSR was released in October 2004, with a Cosworth Duratec engine and was available from the factory in either or form.
Engines
Lotus TwinCam Early cars used the Lotus TwinCam engine (subsequently manufactured by Vegantune), followed by Ford Crossflow engines.This paragraph largely draws from Chris Rees' bookCaterham Sevens The Official Story of a Unique British Sportscar from Conception to CSr, published by MRP, In 1977 it was announced that Caterham Cars had taken over the rights to build and develop the Twin Cam engine. Caterham also had the big-valve version (with twin Dell'Orto carburettors) emissions tested and obtained a certificate of compliance. In the end, Caterham had engine tuners Vegantune build the engines, using reconditioned twin cam heads, to supply the very important Japanese market. Caterham also had Vegantune develop a version of the Twin Cam using Ford's 1598-cc block (rather than basing it on the earlier 1498 cc unit) with their own, improved DOHC cylinder head. Called the VTA, this variant launched in 1983. Supplied to Caterham Cars as a replacement for the Twin Cam in the Caterham Seven, the VTA featured belt-driven cams. The engine used the later Crossflow block and displaced 1.6 or 1.7 litres. Power was . Around 40 units were supplied to Caterham but quality control was very uneven and Caterham eventually switched over to the Cosworth BDR engine or the single-cam 1700 Supersprint. The first Cosworth BDR-engined Sevens appeared around 1983, in 1600 cc form, followed by 1700 cc versions three years later.
Vauxhall By 1990 the top of the range engine had become the two-litre Vauxhall HPC, as fitted to the Vauxhall Calibra, producing 165–175 bhp. A few HPC "Evolution" models were built with engines developed by Swindon Race Engines producing between and . In 1993 Caterham created the JPE special edition (named for Formula 1 driver Jonathan Palmer) by using a two-litre Vauxhall Touring Car engine, producing around and reducing weight to around by such measures as removing the windscreen in favour of an aeroscreen. The JPE was quoted at 0–60 mph times of around 3.5 seconds and, with Jonathan Palmer at the wheel, set a 0–100 mph-0 record of 12.6 seconds. Around 1997 the cross flow range was replaced by 8v and 16v Vauxhall units which, in various guises lived on until the end of the VX-powered Caterham Classic, in 2002.
Rover The Rover K-series made its appearance in 1991, initially as the 1.4-litre engine from the Metro GTi. This engine became the backbone of the range for the next 15 years. The 1.6-litre K-series appeared in 1996 and the 1.8-litre a year later. 1996 also saw the addition of the 'Superlight' range, a range that successfully focussed initially on reducing weight and subsequently on the bespoke tuning of the K-series to ever-higher outputs. Weight was saved by removing the spare wheel (and carrier), carpets, heater, and often the windscreen (replaced with an aeroscreen), hood, and doors. Lightweight "Tillet" GRP seats were usually fitted along with carbon-fibre front wings and nosecone (note however that items such as heaters and windscreens could still be specified by the Superlight customer if they so wanted). The wide-track suspension was added to the superlight, increasing the track at the front to match that at the back. The later Superlight-R offered the dry-sumped VHPD (Very High-Performance Derivative) variant on the 1.8-litre K-series. Output was now up to around , in a car that now weighed as little as .
Three years later Caterham took the same concept to a new level and created the iconic Superlight R500, still based on the Rover 1.8-litre K-series but now tuned (by Minister Racing Engines) to around at 8,600 rpm in a car weighing just . The R500 was initially available in kit-form but quickly became a factory-build only item. Quoted performance figures are; 0–100 mph in 8.2 seconds (although EVO magazine quotes 8.8 secondsEVO Magazine, Issue 100, January 2007. Published by Dennis Publishing Limited). The engine required frequent "refreshing" in order to keep it on the road and a series of engine revisions were undertaken throughout the R500's life in order to increase reliability. This culminated in 2004 with perhaps the most extreme production Caterham of all; the R500 EVO was bored out by Minister to 1,998 cc and delivered . At £42,000, the R500 EVO sold poorly; it is believed that just three were sold. It did, however, succeed in setting a series of performance car benchmarks several of which last to this day; the 0–100 mph-0 record was set at 10.73 seconds (in second place was a Ferrari Enzo costing ten times as much) and, until the end of 2006 it remained the fastest production car timed by EVO magazine around the Bedford Autodrome West Circuit, ahead of a Porsche Carrera GT. Only the Radical SR3 1300 has subsequently posted a faster time than the R500 EVO.
Ford After the demise of Rover and Powertrain, Caterham started the process of phasing out the Rover K-series engine and replacing them with Ford engines; the Sigma engine for Road sports and later 270 and 310 models, and the 2.0-litre and 2.3-litre Duratec engines for the more powerful Superlight, CSR, 360, 420, 620 and Super Seven 2000 ranges.
In 2013, the 620R had installed a Ford Duratec direct injection supercharged straight-four engine rated at at 7700 rpm and at 7350 rpm of torque.
Suzuki-engined models
In 2013, Caterham also launched the 160/165 at the opposite end of the spectrum. This used a Suzuki 660 cc three-cylinder turbo K6A engine, producing , with S3-style body work only. The live rear axle and transmission were borrowed from the Suzuki Jimny. The model was only available in S (road) specification and continued until 2018. UK examples (160) have a full windshield; European export models (165) were only equipped with a small "aero screen" as the windshield frame did not meet EU field of vision requirements. When European pollution and fuel consumption guidelines testing were changed to WLTP (from the earlier NEDC) in September 2018, the 165 and the 355 both had to be discontinued in mainland Europe as Caterham was unable to meet the new requirements.
The 160 was replaced in 2021 by the 170, available in both R (track) and S (road) specifications. The 170 uses a newer Suzuki 660 cc three cylinder turbo R06A engine, producing ; this car meets the WLTP testing requirements and is available to the same specifications in continental Europe as well as the United Kingdom. The 170 features narrower front and rear bodywork resulting in the smallest Seven Caterham have produced, and the lightest of the current range, weighing in at in R specification. Again, this variant is only available in the S3 body. In 2022 a further variant, the Super Seven 600, was added: this features the same engine and chassis, but with more traditional clamshell front wings and a variety of other heritage styling changes.
Motorcycle-engined models