I didn't find topic of this thing but:

Sometimes when i get phoenix car ''Not spawned'' that car goes normal then i go on that freeway (closer wangs cars) and my car go like 5x faster and then server shutted for me down then i join again and everything like normal...

this bug happened me twice

Maybe your CPU is overloaded,
next time open up your Gta San Andreas then open task-manager with STRG+ALT+DEL.
Right klick on San Andreas in the list go down to "goto process" then a new list comes up then again right klick on Gta San on the list go down to "membership set" then unmark "CPU1"(Cor1) and play normal.

Ok thanks

Grand Theft Auto: San Andreas has problems running on more than one core, please make sure that you're running the game on one core to avoid any process speed-up issues.

Thats what I exapmle JaTo