Sat one of these courses at the weekend in N. Ireland after being clocked at 42mph in a 30mph zone back in the summer - I wasn't even in the zed but an automatic Honda CRV!
Only bit that really perked my interest was when the instructor told a story about how some young lad had taken his new high powered sports car out for a spin and lost control of it coming off the road into some trees. He then showed pictures of the accident and yup, you guessed it, the car turned out to be a 350z (or Nissan 240x as the instructor called it! ). It was sad to see a zed all smashed up like that