First of all, a Jetta is midsize - even that's a stretch, as the most direct comparisons to Jetta are Civic and Corolla, two obviously "compact" cars.

But Hertz gets away with calling Corolla a mid, so in their nomenclature that probably makes Jetta a mid as well. (Car rental category-creep is another topic, but there's no way they can consider Corolla and Jetta in different categories. Since Corolla is the Hertz.com poster child for the midsize category, that makes the Jetta a non-upgrade.)

But more importantly that that, I would not have accepted a piece of crap car to begin with. OK, at a huge airport where demanding a car swap is going to cost me 5-10 minutes, I'd consider it. But not at an HLE where I'm the only guy there, there's no #1 Club Gold service anyway, and where I can see other cars on the lot that aren't damaged.

For the gas, I always check the fuel level, especially at HLE's. On occasion, I'll get one that isn't full. They're usually pretty cool about it: the most common "fix" is that they simply mark an outgoing fuel level that's generous for the renter. For example, if the tank is 1/2 full, they'll note the record as 1/4 full...I bring it back somewhere in that range and everything is fine. Alternatively, I suppose you could offer to go across the street and fill it to get an actual receipt.

In general, I've had good experiences with HLE's - usually they are laid back and easy to work with.