These are wonderful little cars, and the 3 cylinder models get fantastic MPG especially the 5spds.

BUT:  The frames rust out commonly on these cars, so be aware and ask for pictures of the front frame and suspension area.

Also, these are NOT a replacement for your BMW or Caddy, they are baseline cars, you WILL hear every bump and groove in the road, as well as the constant hum of the tires (NO soundproofing).

These cars are NOT racecars, and if you drive them like a racecar the mileage WILL suffer.

They WILL burn exhaust valves, and run poorly.  They will most likely use or lose oil, so you the proud owner will have to actually check th oil at LEAST once a week.

They are currently very cheap to fix, IF you fix them yourself, if not...bend over and kiss the shop owners feet.

The best models are 1989 to 1994, stuff changed in the 1995 up models that hurt the fuel economy, generally speaking the 94 and earlier are the only ones to get 45-50mpgs and sometimes better (XFI models),  95 and later had bigger tires and were heavier cars so they tend more towards the 35-40mpg range, the 4 cylinder models of course get even less.

Also BEWARE, the seller who says 50 mpg but words his ad such that it is fairly obvious he has never driven the car, and is probably just flipping one.

The convertibles RARELY can get 40+MPGs, again, heavier cars (no roof = beefier floor & body).  The auto convertibles get around 35mpg, 5spds better.

These are, of course, MY opinions, based on my experience alone.  I have owned (and driven) or serviced at least one of every model metro, and I have considerable experience on these little cars.

Hope this helps you make a good decision.