As was said before, just because you have 4 cylinders doesn't mean that you are more enviroment friendly or get better mileage.
Look to Honda. All their cars right now are LEV, with the Accords and Civics being ULEV. Also as mentioned, the Insight is SULEV and gets excellent gas mileage.
1985 500SEL 124k miles
2001 Honda Civic EX