public OnPlayerStateChange( playerid, newstate, oldstate )
{
    if( newstate == PLAYER_STATE_ONFOOT && oldstate == PLAYER_STATE_DRIVER ) // Check if the player was in the vehicle as a driver.
    {
        // If engine is on
        SendClientMessage( playerid, 0xFFFFFFFF, "SERVER: Don't forget to turn the engine off!" );
    }
    return 1;
}