I bought this car with 190,000 miles on it, so it's hard to determine if the condition of the car was due to how it's manufactured or because the way the previous owner drove it. Nonetheless, when I got it, the original paint job was faded. I think this was because he left it out in the snow. However, when you wax it, it looks somewhat new.
I don't think there was any major mechanical problems with the car. other than it had to be smogged, which cost $900. I think it could have cost less, probably at most $300. This was to replace the modified intake. Other than that, I think the only other major problem is that it doesn't start well when it's left in the sun. I've heard this a few times with this type of model. I believe it's due to a fuel injection sensor. I took it to a mechanic and he agrees. This makes me wonder a little whether I would want to buy future cars with fuel injection. However, it could just be the prelude. At 190K, there is a slight transmission problem. The transmission "kicks" when it goes from 1st to 2nd and is a bit rough.
However, once it gets going, it performs excellently. And I think that's the thing with this car. The only real problem is getting it started after leaving it in the sun. But once it's on, it'll stay on. It's very smooth on the highways and roads. Everything else works mechanically and I would not hesitate to drive this car across the country. I would only hesitate to turn the car off not knowing, if it'll be harder to turn back on.
This car has 210,000 miles on it and has been through 2 accidents, both not my fault. It's not worth it to get it fixed because it has so many miles, but I'm quite surprised it still runs so powerfully given it's been badly bruised. This is what gives me the confidence that it is truly a good solid car. (Although, I think there could be a better job done at the fuel injection thing and restarting time).
Your current mechanic knows nothing. All you have to do is replace the Main relay. It is located under your Drivers Side Steering Wheel. It should run you about $70.
We had the same problem on a 1992 Honda Prelude SI with 160K miles. It would start and run fine on cool days. On hot days, would not restart after sitting in sun. Problem was main fuel relay that is located under the steering column. It is easy to change and sells for around $75 dollars. You can also tap it and it will likely engage until you get the new part.
Your prelude does not have a transmission problem. that's just the way they were made. the automatics were made to shift harder to make it seem like they were more "sporty" so don't think you need to fix the transmission cause that's just the way they are supposed to be.