I ran my 308 Dino on exactly that philosophy, worked a treat, only draw back is an annual check up will probably mean a couple of days off the road while bits are found so you might need spare wheels.
I paid £13k for it, it lived on the street in south London and was my daily smoker (yes I commuted to work in it) and ran up a good 25k miles. Spent about £3k over 18 months or so £1k of which was the diff rebuild when I bought it because it had been sat too long. Sold it for £12,500.
The M3 I was thinking about buying would have cost an extra £1k to insure (I was 24) and would have depreciated by at least £3k, and servicing wouldn't exactly have been free!!!
Of course a Kia Pride would be cheaper but it misses the point!!