With his trainer, Cruz Ramirez, Lightning leaves the lab and tries to do some real racing outside - but spends his time teaching Cruz how to drive.
For a taste of real racing, they enter a local race in disguise, only to find it's a demolition derby. Cruz ends up winning, and Lightning runs out of patience when he realises the training is never going to help him beat Jackson.
Lightning apologises when he offends her. She tags along now as a friend and not as a trainer. Lightning has an idea and tracks down Smokey, Doc's mentor. Smokey tells him he'll never be faster than Jackstorm - but he can be smarter.
For a final practice race, Cruz overtakes Lightning at the finish and wins, destroying his confidence.
At the big race, Lightning starts last after missing qualifying. Smokey takes a seat as his pit crew chief, and guides Lightning up the pack. Jackson still performs a faster lap, and Lightning has a better idea.
He pulls in to the pits and swaps his place with Cruz, who takes over his number. Smokey quits. Lightning takes Doc's old position, and guides Cruz through the pack until she is just behind Jackson. She drafts him, which seems to be a new technique to these cars, then when he tries to push her into the wall does a trick she learnt from watching Doc's old videos, and sneaks in to grab the win.
Tex is impressed with her win, and strikes a deal with Sterling to add her to his team.
Back at Radiator Springs, Lightning and Cruz line up for a race. (Shame it wasn't the whole crowd racing one last time for fun, which would have been a better end, more emotional and a little light-hearted. But harder to draw I imagine.)