It doesn't even come close to original or unique and it's pretty repetitive (how many obstacles and disadvantages does one kid have to face?!?!), but it's loaded with fighting spirit and nail-biting races. I'm kind of a sucker for this sort of story so I don't know how much you should trust me, but I found the story entertaining and heartwarming.
It feels a little young and simple, but there's plenty of action and drama and excitement. It starts with Capeta in elementary school and follows him through his mid-teens. Toss in the additional weight of a bunch of financial difficulties with his never-die attitude and you've basically got Rocky (or Hajime no Ippo) in a go kart. It's not an unfamiliar story: a humble working class kid (Capeta) with a natural aptitude for a sport struggles to climb to the top. Personally, I'm not big on racing in real life, but I found it really fun and exciting here. Capeta is a blue-collar, work your hands to the bone sort of sports anime about racing (mostly go karts).