I'm familiar with this sentence
He is a tough guy to deal with.
And I understand why there should be a with after to deal. My teacher used to say that you could un-shorten the infinitive to an attributive clause like
He is a tough guy which you will deal with.
But this sentence is confusing to me,
He has enough money to buy a racing car (with).
First, the infinitive can be unshortened to
He has enough money with which he can buy a racing car.
But it could also be unshortened to
He has enough money so that he can buy a racing car.
Does that mean I can use ....to buy a racing car and ...to buy a racing car with?