I have owned a 2002 Saturn SL2 (manual) for 235,000 miles now. It is still getting great gas mileage, 36-37 mpg average without AC use on 80% highway travel (I massaged 42 mpg recently on an all highway trip). I'm at the point now of either rebuilding or replacing.
If I do replace, I'd want a car with the same or better safety since I'm going to be carting kids around in it. But I don't want to have to deal with a tree-trunk thick A pillar or a car that's going to try to out-think me. So it appears I'm looking at a range of 2000-2008 model year cars. I am shying away from a diesel because I tend to drive 75-80 mph whenever possible (my understanding is that diesels lose mpg faster than gas cars at such high speeds).
My question is, can I top what I've got? I have the ability to rebuild or modify a car to get the MPG needed.
Of course you can top that. Immediate thought is to find a low mileage SL1 rather than your SL2 w/ the DOHC, it will manage 2-3mpg better and be the identical vehicle in every way except for just a few.
Secondly, I don't think at that mileage you'd benefit much from a rebuild. Not unless you took on the challenge/expense of new suspension, bushings, brakes, trans, engine, etc. At that price point, you'd have $6-8k invested. Just not worth it. You can likely find any nice Saturn S-Series with less than 100k miles on it (or just over) in the $3-4k range.
Aside from that, if you're not looking at cost of ownership throughout the vehicles life, you can buy many newer models and top 36-37mpg average. Yaris comes to mind first. Cruze's can be found pretty cheap, Fiesta's aren't terrible.
I can agree with the above post... Why not find another Saturn? But if you are going to spend a lot on a new car($6-8k) you might be better off to rebuild your Saturn... You could do some research and gain both power and fuel mileage and still have a car you are somewhat familiar with... Plus i think you can eliminate the oil leak(typical saturn issue) during the engine rebuild... Search SaturnFans.com | The Saturn Authority for Saturn Enthusiasts. for info...