and that right there isn’t how you describe a 510. a 510 is expected to be quick. its a light car and most of them have an engine in there that puts out a lot more then stock power. not all of them are going to run 10s but most 510s you would ever see are prob 13 second cars. maybe you just don’t pay any attention to the 510 scene, but i love old japanese cars, esp datsuns, and the 510 is deff not a sleeper.
as far as what i’d consider a sleeper, the volvo wagon is a great example.