I would do a little research on those specific year and model cars at
www.carpoint.com
They have a reliability section and list common problems with the particular year and model car. I wouldn't base my decision purely on it, but its a good guide.
The 4th generation Maximas MIGHT require premium gas, I know the 5th generations do. With gas prices as high as they are and continually rising, I would hate to spend that much money on gas for a beater car

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From my experience and friends and family, Toyota makes a really well built car that lasts. My dad has an 89 Corolla still doing good (knock on wood) and my best friend's family has a 92 Camry with over 200k miles still running fine. As long as you keep up with it maintence wise, you should be fine. I don't have to much experience with Nissan, but i'm sure they are up there too.
I would definately avoid the 2000 Ford Focus if your looking for a reliable beater car. My friend has one and uses it to deliever pizza in, and has had so many problems with it. I know when my cousin was thinking about getting one he researched the reliability of them and was quickly drawn away from them
