[juio1234]

I mean when the the car doesnt change gear it just stays in 1 gear and you dont hear it change

[Mike Garber]

That's not a SA:MP bug....
It's a GTA bug, often happens if you hold SPACE (handbrake) while holding W (Throttle)

[Mah_Kylling]

Maybe he means when you're a passenger.

[Diablosrouge]

If you're talking about that bug in which you dont hear the main sound engine, but just the background noise of the car, like if it was floating, yeah that still happens.
Confirmed.