@Sir Bacon Any level of alcoholic intoxication renders you unable to drive properly. Even if you just have a couple of beers, your ability to quickly respond to unexpected situarions diminishes, making you prone to accidents even if you're driving "properly" at a moderate speed. Remember, driving does not depend just on you, you always have to assume the road is full of bad drivers and act accordingly. That's whats called defensive driving, and a single beer could hinder that ability if, say, you're driving at high speeds on a freeway or any other road. Think of it this way: from your first drink, you're already too drunk to drive, even if you feel otherwise. That's what we are taught at the faculty.
The short answer is that he's that strong, but I like the long one better. Drink responsibly and always hand the keys.