Its very difficult to get meaningful statistics regarding types of failure between makes. Statistically a honda and a toyota are more reliable than anything else, while a VW is as reliable as a ford and probably more so than an audi, whereas the common perception might be audis are most reliable.
But what if you factor in price? There is no TCO stats for cars so far as I'm aware. As such most people's experience of cars is anecdotal based significantly on their own experience and (biased) opinion.
Taking the common perception of audis as well made cars, they're also flippin expensive, which goes for the servicing too. So when you get someone saying "audis are reliable" figure into it how much they spend on it!!!
The flipside of this is that a renault is perceived as a cheaper car so more likely to be scrimped on servicing with more complaints made when something needs replacing; whereas an audi owner would just wear it: they'd be more ashamed to say their audi was duff than admit they had to replace a worn part.
To return to my original point the stats are impossible to get to as they're commercially sensitive. But if the average renault owner spent the same on their car as did an audi owner, including parking it in a posher area / garage, you can guess what the impact would be on overall reliability.
And there's no substitute for doing some of the work yourself. I bet a renault is easier to work on than an audi or a merc
... lets face it, you buy a renault coz ya poor and have a dig at it to make yaself feel better