I drive a regular ol' Hyundai. I've had it for several years, and it's always been good to me. I think that it's of a certain age now, and things may start to degrade, slowly but surely. A few weeks ago the car started to overheat. I don't know anything about cars, but my next door neighbor, who drives taxis, said that it sounded like the thermostat. We took his word for it and bought the $14 part. Now, to install it...The internet told me the thermostat was located to the right of the engine block. With that our only clue, we set about searching for it. To make a long story short, we were able to replace the thermostat, which did end up being the problem. It took us probably 3 hours (we had to do it twice because the first time we installed it we did something wrong and had a leak at the installation point).
Moral of the story? Most people won't dare attempt repairs on their car, instead spending tons of money to have a mechanic do it. If you know what the problem is, and the part is reasonably accessible, it's really not that hard to do it yourself. It'll save you hundreds of dollars, and you might even have a little fun tinkering around in there.