Some great advice for all of those fresh tech millionaires out there is that you should always buy a car at least an order of magnitude below what you can afford, for exactly that reason.
I still use the one pay check rule for cars. If it costs more than I make in one pay check, then I can't afford it. It has been a good incentive to get better pay checks. :-)
That's probably good advice for anyone: don't stretch yourself financially, especially on depreciating assets.