It's not about how competant they are on car X, Y or Z. It's about experience on the Renault F4R engine. Taking the above example, just because Fernando Alonso's chief mechanic has done F1 engines for the past however many years does not automatically mean he:
a) Knows that the 3 locking tools exist for a puny little clio.
b) Knows the quickest way to do it (engine in/out) as this only comes with doing it a few times.
c) Cares about doing it properly when he needs to do a cambelt on Mr Smith's 200k 599 GTB for when he collects it later this afternoon.
d) Other things I have probably forgotten about or don't know, as I've never done an F4R cambelt.
As has previously been said the other thing is r.e. locking tools. You can't do the job properly without the correct locking tools, unlike other engines where you can bodge it by putting tip-ex marks everywhere. The locking tool for a Vauxhall Astra 1.8 is £11.99 and this also fits about 20 other vehicles. That's an alright investment for a garage. The locking tools for a Renault F4R cost £120 and IN THE ENTIRE WORLD fit 3 cars: the 172, 182 and the Formula Renault 2.0L single seater racing car. That is not a good investment for a garage thus virtually none of them bother. Paying £500 (whether you're paying or the garage is) for someone to not use the right tools actually sounds quite amusing.
99.999% (made up figure alert) of warranties do not cover "wear and tear." E.g. brake pads wearing out, tyres wearing out - fair enough you may think. Does it cover the bearings in the pulleys wearing out? Does it cover the cambelt failing due to normal 5 year/72k mile wear?
If they are busy selling cars worth 100k, are they going to be that bothered about doing a proper cambelt job on your puny little clio? Sure this works the other way around, if they're selling Italian supercars then they'll be pretty desperate to get a 4k Clio of their hands.
Even if you ignore ALLLLLLL of the above this just sounds odd to me. You can:
Pay £500 for a monkey to do it
Pay £500 for a Ferrari/Lambo/Whatever specialist to do it
Pay £500 for a Renaultsport Clio specialist to do it
Who cares about their reputation the most? (It's not the Ferrari/Lambo/Whatever dealer when we're taking about a Clio & it's not the random-garage/man-in-street)
Who is most likely to do it correctly (Durrr the Clio specialist who only does Clios day in, day out)
Who is garunteed to have the correct tools in the first place (Duurrr Clio specialist)
Good luck. I personally am not saying don't let them do it. I'd just ask them how many F4Rs they've done and which locking tools they have. If they even know what an F4R is (why would a Ferrari mechanic know a Clio engine code unless they know a bit about them?) and say "the RS Clios absolutely require 3 specialist tools, all of which we have" well then that's a bit more confidence.
