Easiest way is to bump up to 18v if it is a 12v model. Mcqueen was a 12v stock, he is now up to 18v & it moves pretty good now with no reliability issues at all. My son learned how to drive before he learned how to ride a bike LOL.
The next round of upgrades is currently shipping via UPS, & will be putting them in this weekend.
The best place I've found is
http://forum.modifiedpowerwheels.com/
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