The race quality is simply down to packet size and frequency of information transmitted. There's nothing about the physics there, the physics is all calculated locally. The higher qualities result in smoother movement of opposing cars, unless you can't meet the bandwidth requirements. At which point it goes pretty badly downhill, you can't keep track of everyone else, and you probably can't upload fast enough to everyone else either so you start jumping around for them too.
I think the highest quality setting (Very High) is overkill and risks problems. I'd suggest using High. If serious problems for multiple players are detected during warmup then POSSIBLY the room could be moved to Normal. I'd suggest that at least 3 or 4 players should be affected before considering this. If it's just one guy, sorry but you're going to have to take one on the chin for the sake of the other people's smooth racing.