And that small number made it very easy for some manufacturers to make a special serie. So the buyer of an AR155 Silverstone found lying in his boot some pieces of plastic and about 70 rivets...
On track however these pieces made a very effectif spoiler and giving the AR155 an advantage of 0.5 sec a lap.
"Basically production cars" is rather amusing when a TWR BTCC Volvo (Rydell) is now (mai 2008) available for the modest sum of 300.000 Eur. For this price you may use it on trackdays but you are prohibited by contract to race it.
The bodyshell alone of this car is worth around 100.000 Eur and it is 25 kg lighter than any other S40 ever build (a part from the batch of 10 TWR cars).
I won't go into detail about engine and gearbox but just know that the Belgian raceteam that tried to race a 1997 TWR S40 stopped racing alltogether after 3 of the 15 races: they raced with the sprintgearbox (build for 20 min sprints) in races lasting 2 hours. It broke after half an hour on the 3 races when they were leading.
IMHO you need to redefine "basically the same": the "basically the same" suspension components and unsprung weight of each wheel of a TWR race car is about 4 times lighter than OEM, 20 to 50 times more expensif and most items (trackrods, triangles, dampers, springs, uniballs) have as lifetime 1 raceweekend.
:-)
The "etc" you mention so causally needs a budget of about 10.000 UKP
*per* raceweekend *per* wheel.TWR was known never to let anything unused of its budget. Sadly for TW he did the same with Arrows and Cosworth and it boomerranged on his head.
I doubt that the TWR Vitesses the aerodynamics were that advanced.
Windtunnels were not yett as avaiable as they are now but nobody had/has to teach TW a lesson when it comes to touring cars racing and team leading. TW is known in Belgium as a ruthless individual often kicking out pilots when they had an own mind or when it was in his advantage to do so. A certain Ph. Verellen at Spa springs to mind: the chap was leading in a TWR-car and faster than TW himselves. Ego's being what they are: Philippe found he was out of a drive at sunday.
Stating that a TWR racecar is basically the same as the roadgoing version of it remains either not knowing TW(R) either insulting TW(R).
Tom De Moor