Who are these cars considered sleepers by? I'm pretty sure most car enthusiasts would know what they are looking at... with the exception of the Accord 2.0T, which I don't think anyone knew was a thing or would consider a sleeper.
I think sleeper by most definitions does not include enthusiasts as the people who get to rate something as a "sleeper". We know what we're looking at
- Everyone thinks a Ferrari is fast because it looks fast (enthusiast or not) - not a sleeper.
- Mercedes E63S AMG - some (not enthusiasts) may pass this off as just a Merc sedan.... until it blows the doors off their camarustang. This is a sleeper (barely)
- Old B5 S4 in good condition - most people think, "Old audi". We see an upgraded exhaust and hear lots of intake / spool - "That's probably fast" - sleeper.