However, there is another side to the kit-car industry, where the manufacturers are genuine engineers, the workshops qualify as factories, and the cars make the pulse race. With certain makers the term 'kit' is a misnomer - a customer's role in the construction can sometimes amount to little more than bolting the wheels on.
So, why not sell fully built cars and be done with it? 'Type approval', that's why not: a set of regulations to which all new cars sold in Britain must comply. It governs everything from the specification of the glovebox hinges to the way a car must crumple in a head-on, 35mph accident.
But last year the Government came over all kind-hearted towards low-volume car makers and excused them the more costly parts of type approval. A lot of kit-car makers then changed the sign on their doors to 'specialist car' manufacturer.
Westfield, a Midlands-based specialist car maker, has become the first to benefit from the new low-volume type approval regulations. Its ZEi two-seater roadster is now in a handful of showrooms. The other models in its range remain the self-assembly variety.
If the Westfield's shape looks familiar, it is because it is based on that of another low-volume maker, Caterham. And the Caterham (a version of which will soon have type approval of its own) is a copy of the Lotus 7, a feature of The Prisoner television series. The main difference between Westfield and Caterham is that the former has bodywork made from glass fibre, while its rival has an aluminium body.
The Westfield is small, low and light and does not need a thundering great engine. (Though Westfield sells a model with an earth-shaking 300bhp V8.) The ZEi uses an off-the-shelf Ford unit, the 130bhp 1.8-litre four-cylinder 16-valver that powers the Escort XR3i and the new Mondeo. Full marks for convenience, fewer for refinement and aural satisfaction. Ford still cannot replicate either the zingy smoothness of a Japanese engine or the passionate growl of an Italian unit - either would do, the Italian preferably.
Fortunately, the Westfield's light weight means that working the engine hard is not a prerequisite of ample performance on the road: there is plenty of scope for scaring yourself down deserted country lanes using only 5,000 of the 7,000rpm available to you. Throttle response in the low-to-middle speed ranges is swift and eager. The sensation of speed is heightened by sitting so near the ground: the road zooms by when you are almost able to reach out and touch it. So, too, do trees and fields above and around you - cars like this should ideally be driven only with the top down. Besides, the Westfield's hood is so fiddly to erect, and so claustrophobic once you are beneath it, that you end up using it only in emergencies.
Making full use of every inch of your side of the road by exploiting the car's compactness and the accuracy of its steering is an essential part of the Westfield experience. But before you rush out to buy one, bear in mind that the Westfield comprises only an engine, gearbox, four wheels and a couple of seats. The only luxury electrical item is the heater fan. Getting in and out is a test of dexterity. And long journeys are noisy, breezy and chilly. Everyday transport for the dedicated maniac, then. No compromise, terrific fun.
Westfield ZEi pounds 14,688. Engine: 1.8-litre, 16-valve, fuel-injected four-cylinder. Power: 130bhp at 6,250rpm. Torque: 119 lb ft at 4,250rpm. Five-speed manual gearbox, rear-wheel drive. Performance: Top speed 110mph, 0-60mph in 6.7 seconds. Fuel consumption: 34-44mpg on unleaded fuel.
Caterham 1.4 K-series pounds 13,254. The car on which the Westfield is modelled. Has an aluminium rather than glass fibre body. Its 1.4 litre Rover engine more refined than its rival's Ford unit. A kit car at present, but should soon qualify for low volume type approval.
Mazda MX-5 pounds 15,780. Not as fast or as nimble as the Westfield, but infinitely more practical and refined. Enormous fun, shame about the price.
Peugeot 205 CTI pounds 14,195. A different class of car entirely, but has some similarities to the Westfield - the top comes down and it's nippy.