Tried to get a car from the auction house on multiple occasions. Not the most expensive or rare car, but multiple bidders nonetheless.
If you get overbid and return to the auction house and try to set a new bid you get an error that it has failed. You return to the auction, it states for example, last bid 15.000. You try to bid again (16.000) and it fails again. You then must return to to list of all auctions, select the auction again and only then you get to see the real latest bid. Bid again, but chances are it will fail again, because other have bid in the mean time.
Because of this it is impossible to partake in a bidding war, because bid prices are not updates sufficiently. Really inconvenient.