The ETK I-Series I agree with, but considering that the base model ETK 800 has a 0-60 time of 6.8 seconds it isn't slow at all.
Old Pessima, but with the diesel mod from the repository. There is a 1.9l N/A version with like 70 hp i think.
The I6 Moonhawk is pretty good for cruising. In urban environments, I'd say either an ETK I-Series 2400 (great fun for slow-speed gymkhana-type stuff) or a Covet.
My vote is for the Base and Luxe Miramar. They are pretty light with limited traction and bouncy suspension, so it's quite fun to peel around corners in a sub-100 hp car. If you want slow car fast try stripping a Covet LXi, give it a 5spd with race final drive set to 5 on top of race tires and race springs/dampers. Go Kart.