Which Mario Kart character are you?
Toad is considered a lightweight kart. He can accelerate the fastest but his top speed is the slowest. His handling is also the worst. He will spin out of control when a heavy kart collides with him.
Mario is a medium weight kart. He is the most balanced between the lightweight and heavyweight karts. Medium acceleration, medium top speed, medium handling.
Bowser is a heavyweight kart. He takes the longest to accelerate but has the highest top speed. When he collides into the lightweight karts, he is not affected.
Each character has its own good and poor qualities. Do you take a while to get going, but once you're moving, watch out? Are you usually the quickest to get going and agile, but easily distracted and knocked off course? Or are you steady-as-it-goes? You might not be flashy, but you get the job done through small, incremental improvements.
Whichever character you are, capitalize on your strengths, adapt to your weaknesses.