The kart you get does matter. They said they will be rebuilding the motors on just about all of them to get them all up to par. Right now though there are karts that are dogs, karts that are fast, karts that are loose, karts that are less lose (you aren’t going to find a tight go kart 
) .
We also found that the tires can get too hot, not sure if the tires are brand new or not though.