I immediately assumed he was talking about the Sabre GT as soon as he said "modified version of another car". I didn't think it was underrated, but since you guys apparently passed over it and went straight to Sultan (RS), I guess so. It not only has the normal Sabre, it also has the rusty, beat up Sabre.
Tycek got it. It matches all the clues.It's one of the rarest cars on IV.Outmatching the Sultan RS since everyone knows about it now.Used by the albanian mob,it drives around bohan and has some great speed and handling.