Fun and Sporty (hopefully convertible)

This is a tough one. Fun, reliable (or at least fairly simple to repair), four-seat convertible for $15,000?

The closest fit is probably a Ford Mustang, though I suspect it's no more your sort of car than it is mine.

Next closest would be rolling the dice on something European (3-Series, A4, CLK, 9-3, C70, Eos).

Drop the convertible requirement, and the four-seaters closest in character to your favorites are the Mazda RX-8 and Scion FR-S (which would likely be a bit over your budget, but some asking prices are close).

The Scion is noisy, not very comfortable on the highway, and has a very tight back seat.

The Mazda is both more comfortable, more practical (roomier and easier to access rear seat), and more agile, but has poor fuel economy and just so-so reliability (including some engine failures). I'll soon own one myself anyway. Quite a few owners seem to do their own repairs, as rotary engines really aren't all that complicated.

The fewer miles you drive a year, the more sense the RX-8 would make.

If RWD really isn't suitable for your needs (in Colorado), perhaps a Subaru WRX, MazdaSpeed3, or Civic Si.

We don't have any data on the C70. Volvos of that vintage tend to be troublesome, though.

An Acura TSX could be fun, especially with a manual transmission.

2005 is the last year for the IS 300, so those are getting up there. A little less of a concern, since it's a Lexus. I wish they had offered the wagon version as a manual. Very tight rear seat.