I've had a 1980, a 1986, and a 1987 turbo. Overall reliability was excellent. My 1980 took more abuse than any car ever should have. I accidently left the radiator cap off before heading out on a 200 mile trip. It was running warm (it sometimes did that) but no other symptoms of trouble. When I finally got to where I was going and heard the hissing, I knew the end was near. It had 138,000 miles and ran perfectly before this. I traded it in on a almost new 1986.
My 1986 was taken off the road at 135,000 miles by a severely left of center pickup truck. Ran perfectly and was the most reliable car I had ever owned.
My 1987 turbo was less reliable than the others but pretty decent overall. It blew an apex seal at around 125,000 miles. Even on one rotor it had enough power to drive the 50 miles back home. What fdcg27 said about cores not being rebuildable is pretty spot on. I tore the engine down, it was horrific inside. Some parts are reuseable but most of the time the housings and at least one rotor gets so scored there is no hope of ever using them again. Usually you have to go diving for new ($$$) housings and rotors, or find one or two donor engines to piece a good one together.
The earlier carb'd 12A engines generally last longer than the later 13B's. I believe the 12A's had 3mm apex seals as opposed to the later 2mm seals. There are some well known rebuilders, Atkins and Rotary Resurrection come to mind. Spend some time on the Rx7club forum, there is a lot of good info there.
The 1980 and 1987 averaged about 22-24 mpg on the highway. Around town, they can be pretty thirsty. The '87 turbo was an absolute gas hog if you were spooling the turbo a lot. All three of them handled great.
I would love a GSL-SE (even though its a 13b) but if I could fine one, I would be all over an early rust free 12A first gen. Super fun to drive cars, and at least around here there are enough of them in junkyards still that parts arent too difficult to get a hold of.
