In Pixar's Cars, Guido is Lightning McQueen's Italian tire-changing partner.
Guido works at Luigi's Casa Della Tires in Radiator Springs and serves as Luigi's assistant. He is a small blue forklift with a strong passion for racing and pit-stop work. Although he speaks very little English, his actions communicate his skill and enthusiasm clearly.
Guido's most memorable sequence comes during the final Piston Cup race. He performs an exceptionally fast tire change for Lightning, surprising the larger racing teams and helping Lightning gain an advantage. The scene turns a character who seemed comic and peripheral into a crucial member of Lightning's support crew.
Luigi and Guido are both associated with Italy and Italian automotive culture, which can cause their roles to be confused. Luigi is the yellow Fiat who owns the tire shop, while Guido is the blue forklift who handles the tire-changing work. Guido's name is therefore the specific answer when the question concerns Lightning's tire-changing partner.