It's a bit scary that they didn't find a hire car of their own make for you to drive around, but gave you a competitor's car to try out!!!

I hope you can either get it fixed or get a new car - an unreliable car is the worst. My first car was a Suzuki Sierra (not sure what it's called in the USA, but those little soft top 4WDs). In the five years I had it, everything had to be replaced at least once, including the head gasket, pistons, bearings, the whole fuel assembly etc etc. One of the funniest problems was when oil was leaking into the air filter and the hot air churned it into margarine!!! Not so funny when I had to grab handfuls of the stuff out of the air cleaner to remove it - I've never eaten margarine since!