B-spec can seem hard depending on which race you start with. The Vitz race can be tough if you don't hit it with enough 'oomph', the British lightweight can be a tough one if you don't have the right car to begin with, and if you jump up to the truck race in Amateur, it can be like running into a buzz saw.
Sometimes they take patience more than anything else, and learning when to pace up and when to pace down your driver. It's not fully automatic (doesn't run well without supervision) unless you have a killer car. Keeping your driver cooled off is tough, especially in shorter races. He gets wound up early in the race, and often finds himself in traffic, making it worse. Then he makes mistakes.