Answer: "más bonito que"
Justification.
That is a comparative sentence. You are comparing "el coche deportivo" which means "the sports car" with a "cacharro".
Cacharro is a despective word use to refer to an old machine, misfunctioning, in bad state, so, definetely a sport car is "más bonito que" a cacharro.
Notice that "más feo que" means uglier than, "menos rápido que" means less fast, and "menos bonito que" means less beautifull, so those cannot be a good answer.