Last night Top Gear ran a section about modifying a Renault Avantime to try and equal the lap time of an Evo FQ300 around the Top Gear test track. While they (unsurprisingly) failed to match the time of the Evo with their ample budget of ?9800 they did run comparative lap times at various states of modification, most importantly on road tyres and track tyres without any other changes.
The first run was the stock Renault Avantime which lapped in 1:42.5. James May decided huge brakes were the best thing for lap time so they fitted a lovely set of AP racing vented discs and callipers and a set of slightly larger alloys with road tyres (which looked like a Dunlop tyre but we didn't see the model, if anyone knows any better please comment below). Thanks to the lack of setup in the new brakes, the added unsprung weight and most importantly the added rotational inertia the modded Avantime actually lapped 2 seconds slower at 1:44.6.
Next they bolted on a set of Toyo R888's and did another lap. This time they improved the time but not enough to regain the lost time from the brakes. The semi slick shod Renault posted a 1:42.7 which means the track based Toyo R888 tyres saved 1.9 seconds a lap - not too shabby for a short lap and no suspension setup changes to take advantage of the tyres extra grip.
The next batch of modifications came in one big lump. They stripped the seats out, replaced the glass roof with perspex and added coilover suspension which allowed them to setup the cambers to give the R888's a better chance to work properly. The result, a lap of 1:38.2, a massive 4.5 seconds faster.
Over night they gave the engine a bit of a fettle and added 56bhp (from 150bhp to 206bhp) which gave them another saving of 2 seconds a lap to 1:36.2. Running out of ideas they stuck the rear wing from a Honda (Super Aguri) F1 car to the roof of the Avantime which made the lap time 0.8 seconds slower. This drew a conclusion to the section.
After a bit of chatting in the studio they ran one more lap with some undisclosed changes. These looked like a new exhaust, the brakes balanced and a wooden front splitter resulting, after some epic driving by the stig, in an ultimate lap time of 1:35.4, meaning they paid ?1380.28 for each of the 7.1 seconds they saved! Better than ?10,000,000 a lap F1 spends at least...
Stock - 1:42.5
AP Brakes - 1:44.6
Toyo R888 Tyres - 1:42.7
Coilover suspension / Stripped seats / Roof - 1:38.2
150bhp to 206bhp - 1:36.2
Honda F1 Wing - 1:37.0
Undisclosed Exhaust plus Splitter - 1:35.4