In order to contain the threat General Motors invested the unprecedented sum of 2.7 billion dollars in their 'X-Car' project. It was rated a worthwhile investment as it was estimated the new-generation cars would ultimately represent 60 per cent of the US market.
GM, characteristically, carried out an in-depth analysis of the opposition and decided upon a design which incorporated front-wheel drive, transverse engine, and a length of 14.76ft (4.5 metres).
After 20 years there was hardly a world manufacturer who hadn't adopted Issigonis' outlook! For the first time four GM marques were participating in the same programme (Chevrolet. Buick, Oldsmobile, and Pontiac), the resulting cars offering several variations on a theme.
The 'two-box' sedans like the Chevrolet Citation were remarkably European looking, and with the e-box' (or 'notchback') Buick Skylark a bewildering number of door permutations were offered, with two, three, four, or five at choice. There were also two-door coupes.
Overall they varied from 14.69 ft (4.48 metres) to 9 ft (4.6 metres). Widths vared from 5.61 ft 1 metres) to 5.67 ft (1.73 metres), and GM even got weights down to European norms, ranging from 2462 Ib (1117 kg) to 2568 Ib (1165 kg) according to model. The aerodynamic co-efficient of the best streamlined model was a reasonable 0.417. Despite of the dramatic 'down-sizing' and trimming the X-Cars conformed to American standards of interior comfort and spaciousness.
The Citation was GM's first essay into large-scale production front-drive vehicles, and to gain interior space the Corporation had sensibly opted for a transverse engine mounting. The gearbox units mounted on the end of the crankshafts, not with gears in the engine a la Issigonis.
The first cars (developed in the early 1970's) used a Pontiac-derived four-cylinder cast iron block or with crossflow head, developing 90 bhp (67 kW) from a cubic capacity of 2471 cc. However, once the 1973 oil crisis receded GM devloped a new 60-degree V6, also with pushrod ohv, a capacity of 2838 cc, and a maximum output of 115 bhp (85.75 kW). The X cars had unequal length drive-shafts (no mediate shafts) and four-speed manual transmissions were standard with a geared-up top to allow quiet cruising and minimal fuel consumption.
There was a three-speed Hydramatic available as an option, something most important to ensure the cars success in the American market. GM adopted a rack-and-pinion steering layout, but at 26: 1 it was very low geared.
There was a powered alternative but when it was fitted the turning circle increased to a whopping 38.38 ft (11.7 metres). A classic suspension layout was chosen: Macherson coil struts at the front, and 'dead' at rear suspended on coil springs, positively located by trailing arms and a Pan hard rod. The brakes were power assisted with ventilated front discs, rear drums, and independent circuits.
Top-end performance tended to take second place (105 mph/170 km/h for four-cylinder models, 113 mph/182 km/h for V6s), and GM were proud of their fuel consumption figures.
The four-cylinder manual models were claimed to consume fuel at the rate of 24 mpg around town (9.80 lit/100 km), and at 38 mpg (US) when cruising (6.19 lit/1 00 km). The overall average was therefore 29 mpg /8.11 lit/100 km. Under similar conditions GM claimed the V6 automatic was good for 23 mpg /10.23 lit/100 km.