I myself have been behind the wheel of my Probe GL '89 for... about a year now... other than a small door defect it runs fine, and like you said, gets great gas mileage. Though what brings me down is that it's little F2 engine only gets up to about 80 MPH. So, I was at a donut shop one day and the guy behind the counter refered me to a sweet little engine that would give my GL a bit more kick, making it a little more washington highway friendly, ha ha ha, though I have yet to purchase and drop in the engine, I am told it will fit right in with all the stock parts. The engine is the Mazda FE3.
Yeah, I too have owned an 89 Probe GL for about a year now. I bought it with 80,000 miles and have since put another 10,000 on it. The driver side door had a split in the weld holding the door together near the door handle, stretching downward for about 6 inches. I had a neighbor spot-weld the door back up and now I notice that the door isn't lining up correctly when closing, causing quite a lot of drive vibration. As for speed, it has never disappointed me. Since I purchased the car it has had the cooling system and wiring/alternator completely redone. For a 20 year old naturally aspirated I4 0-60 time of 8 seconds and a top speed limited to 113 (which I have reached easily) is not bad at all! I love my probe.