I have had a couple issues with the car. I replaced the brakes and rotors when i bought it, but that was my choice. The check engine light is almost always on, but I just ignore it as the car still runs fine and gets great fuel economy without it. I blew a radiator hose a while ago, but that isn't unexpected on a car that is 12. And i blew a brake hose, which also isn't uncommon on a car that is that age, as i have friends with fords, and toyotas, and hondas who have also experienced similar issues. My recommendation is to use high grade fuel when you can, as the car starts really hard and runs rough on regular fuel, and probably contributes to many of the problems others have listed.
Fuel economy is one of my favorites, the city isnt to great with me, i get about 21 mpg, but i do drive with a lead foot. However on the highway it is fantastic. I get at least 38 mpg at higher speeds.
I also love the seats and how the ride feels, you can really tell you are in a luxury car when you are riding in the s40.