[Abagail]

Use this one actually, I forgot to put a key in the other one,

pawn Код:

#include <a_samp>

public OnPlayerKeyStateChange(playerid, newkeys, oldkeys)
{
    if(IsPlayerInAnyVehicle(playerid) && GetPlayerState(playerid) == PLAYER_STATE_DRIVER && newkeys & KEY_YES)
    {
        new vehicleid = GetPlayerVehicleID(playerid);

        new engine, lights, alarm, doors, bonnet, boot, objective;
        GetVehicleParamsEx(vehicleid, engine, lights, alarm, doors, bonnet, boot, objective);
        
        if(engine == VEHICLE_PARAMS_UNSET || VEHICLE_PARAMS_OFF)
        {
            SetVehicleParamsEx(vehicleid, VEHICLE_PARAMS_ON, 1, alarm, doors, bonnet, boot, objective);
        }
        SetVehicleParamsEx(vehicleid, VEHICLE_PARAMS_OFF, 1, alarm, doors, bonnet, boot, objective);
    }
    
    return 1;
}

You can use Y while driving a car to start / stop the engine.