Just spotted this on the Evo forum - made me chuckle (and never want to take my Williams near Renault!). Ive lifted the quote totally from the forum, but I think thats fair as other threads link over to here and to some of my posts!
"The first batch of williams came out when I was working at a Renault dealership. We were really looking forwards to driving one when they came back for servicing. When one did (1k) we jumped in it & took it for a blast & were gutted. Whilst it stuck to the road much better than the valver (thanks to upgraded shockers & a double skinned front & rear subframe (not a lot of people know that one) etc) the peformance was worse than the valver. We put this down to the engine being tight & were not wrong. At 6k it was on par with a valver & at 12k it would outstrip it easily. It got better & better each time it came in.
Our performance test was up a long hill out of Amesbury where you would select 2nd gear at 30mph & floor it all the way to the top & check your speed as you passed a parking sign at the crest. The valvers used to get between 80 & 85mph up the hill, but the williams held our record at 98mph. Very quick car. Even my 306 GTi-6 couldnt beat it (95mph). Top speed can be attained by hitting the limiter in 5th as we found on more than one occasion on the A303 due to the shortened ratio gearbox.
Usuall things that went wrong were wheel bearings, squeeks & rattles (suprise suprise) & the occasional power steering pump failure ( tho that was mostly valvers for some reason, tho not the 19s)
Head gaskets only fail if the wrong coolant is used & its not bled properly. Renault engines are notoriosly hard to bleed & if you get it wrong, or miss just one bleed nipple, kerching!£££. If you buy one, check the colour of the coolant & header tank. If its an orangy rust colour in & on the outside of the expansion tank, then it has overheated in its past & may have had gasket problems or still have them. This goes for the williams, clio valver & 19 valver as all use idendical cooling setups.
Fantastic cars IMO. Get a valver & youve missed out on one of the greats."