Anyone lay their own concrete?

In Wisconsin, concrete is 20,000 psi per building code. Generally its mixed with fiberglass strands to reinforce strength. That is more than enough for cars at that specification. Whats really important is the underlayment. People that pore concrete will know what is best for that area. A good reputable contractor is worth the price. My be able to save some money by finding one that puts up pole barns and get a package price. Make sure you put a drain in the floor.