I have an 11 year old Saturn and get 44 mpg on the highway at 70. I wouldn't give up my safety for 6 extra miles per gallon.
On a side note, I did own a Fiero once and it had TERRIBLE problems with the cooling system. On one fateful night, I lost all of the cooling fluid when I was away from home. I was closer to a mechanic than my house, so I drove it there. I live in a hilly town, so I would drive the Fiero up the hill, shut off the engine and coast down, then start it up for the next hill. One time I did this, I turned the key past the "accessories" mode and into the lock mode, locking my steering wheel, going 35 down a hill. I almost needed a new pair of underwear after that and know exactly how stupid and dangerous this is now.