In answering the question of cost per mile, the most
significant factor is generally depreciation. Obviously,
this is more true for newer cars (more depreciation, less
maintenance) than for older cars (reverse the previous).

Here's my own experience. My first MB I purchased an
'84 300D in 1993. Though in reasonably good condition,
it was no cream puff. Drove it daily until late 1999, when
it was sold because I switched to a more utilitarian
station wagon. I averaged just under $1000/year in maintenance/
repair on the 300D. I did the majority of the work
myself, and insisted on keeping it in top shape. It ran
and drove much better when sold than when purchased.

As for cost. Paid $7500, had no trouble selling it for
$5000. Got six+ years of transportation for $7500.
That's $2500 in depreciation and $5000 in maintenance/
repair. Least expensive car I've ever owned, and it's
a Benz!