The mk1 mr2 is a decent car...mods are a bit scarce for them, but they have a good following and even with their measily 112hp stock...they can really start to move if you get another 30hp...they barely weigh 2000lb...
. They also don't look that great usually...but with a few mods and some rims (15"...even 16" look too big lol) they can look pretty good...
92-96 prelude - nice and easy to mod...and they look great stock or modified.
89-98 240sx - s13 or s14 they all look great and handle great, but in terms of stock power mostly anything for their price is faster.
91-95 mr2 - great car, but 4000 will be hard to find a turbo and even n/a-powered models are rising in value over 4000 for nice ones. power is decent even for the 140hp n/a...and great for the 200hp turbo...along with the fact that you can mod either, quite easily, to produce decent numbers.
87-92 supra - decent car...weighs a bit much, but other than that you can make them into very good looking, fast cars.
86-91 rx7 - steer clear of the turbos and they are very reliable and quick cars.
If you are ok with fwd then you could buy an older sentra for that much money and they can be pretty quick with a little money. Hell for 4k you can get a lot of cars...a lot of decent cars.
Just don't make a quick decision...decide what car you want, research the hell out of it and don't settle for anything but the car or cars you want...