Road test A car with a tuned Ford 1172 cc engine and close-ratio gearbox was tested by the British magazine
The Motor in 1958. It was found to have a top speed of , could accelerate from 0- in 6.2 seconds and had a fuel consumption of . The test car cost £1,157 including taxes of £386. They commented that car could be bought in component form and then it would have cost £399 for the parts from Lotus, £100 for the Ford engine and gearbox and £27 for the BMC rear axle.
Top speed A Seven's top speed greatly depends upon the body configuration, engine power and gearing. Early models with low-powered engines had difficulty exceeding , although a race-prepared Seven was clocked at whilst driven by
Brausch Niemann through a speed-trap at the
1962 Natal Grand Prix. In addition,
clamshell style wings tend to create
drag and generate lift at higher speeds. Cycle wings help alleviate this tendency, and low height
Brookland aeroscreens or the lighter Perspex variants that can replace the windscreen help improve top end speed. Sevens do suffer from front end lift at high speed – the nose creates more lift than downforce at speeds over around , although retro fitted "winglets" may counter this.
Low speed acceleration Nearly all Sevens, due to their extremely light weight (around 10cwt / 500 kg) have excellent acceleration, especially up to , depending on power. The original late 1950s Sevens could beat most contemporary saloon cars—and by the early 1960s, with improved Ford-Cosworth engines could take on most high-performance sports cars with 0–60 mph time in the low 7 seconds.
Braking The less powerful early models had drum brakes all around, in common with most road cars of the time. Later models had front disc brakes. Physics favours small cars in braking and Sevens have excellent stopping distances.
Handling The highest part of the car is about three feet (900 mm) from the road and it has a cloth top and side curtains with plastic back and side windows. The supports for the top and the windshield frame are aluminium. The lower chassis tubes are five inches (127 mm) from the road, while the wet-sump, bell housing, and one chassis tube are lower, meaning the centre of gravity is very low. The front/rear weight distribution is nearly equal and the lack of a boot and small petrol tank assure that it remains fairly constant. It is, however, more front-heavy than more modern high-performance cars.
Suspension In the original Seven, the front lower
A-arm (or "wishbone") of the
double wishbone suspension is traditional, but for the purpose of reducing weight, the upper suspension integrated an anti-roll (anti-sway) bar into a horizontal suspension arm. This approach formed a pseudo-wishbone which was semi-independent in nature. This approach worked well with early cross-ply tyres, but with later radials, the configuration seriously affected its adjustability. For the rear suspension, Lotus originally used a
live axle (or
solid axle). This approach was very cost-effective since most production saloon cars up to the 1980s used these components. A mixture of Ford,
Standard Motor Company and Austin components was used. One disadvantage of live axles is higher
unsprung weight, affecting handling and ride on rough surfaces.
Aerodynamics In general, cars with non-optimised
aerodynamics tend to be free of adverse aerodynamic effects on handling, but the front wheel arches, of all but the Series I, cause lift at high speeds. Like the good straight-line performance, the car's nimble handling is limited in the speed range, and this is not usually important in a car intended for public roads. While the car's frontal area is small, the Lotus Seven has a
drag coefficient (\scriptstyle C_\mathrm d\,) among the highest of any known production car - ranging from 0.65 to 0.75, depending on the bodywork. Additionally, the clamshell front
wings develop lift. This is accentuated by the slight natural lift caused by rotating wheels. Consequently, Sevens have exhibited understeer at high speeds.
Steering The rack and pinion steering provide a minimum of play and friction.
Frame rigidity It is a
stressed skin construction, in which the flat aluminium body panels, and especially the floor, stiffen and effectively triangulate the largely rectangular steel tubular frame structure. This gives a rigid frame with few tubes and very little bodyweight that does not contribute to the frame stiffness. The flat panels avoid difficulties in shaping aluminum sheet into smooth compound curves. On the downside, it does not allow attractive curves or streamlining. ==Mechanical details==