I have owned many cars. None have performed like my Protege5. It is fun; it is roomy; and it has never needed any significant work. I take long trips with it. I use it for weekend ski trips, kayak trips, canoe trips, camping, and every day to and from work. At 90,000 miles, I paid about $1000 to have a total overhaul including new timing belt/chain. Other than that, I've never done anything more than routine oil changes. I don't think the newer Mazda 3 is this good. In fact, it's about $5k more (I bought my protege5 for $14,999) and not as good quality and not as fun. I'm a lucky man! Oh, the cd stopped working, so I have an aftermarket Sony stereo. Everything else is stock.
Nothing. Keep it has is and maintain the low price. Too late, Mazda already split this car into the Mazda 2 (small engine) and the Mazda 3 (large engine).