I find this analogy strangely appealing.

The casual:
Spend most days slouching at home in his sofa, rarely takes his old Volvo out for a spin. If he does, it's to and from teh supermarket. He will not normally wear a seatbelt, feels no social pressure to do so and might only do it for that comforting safe driver feeling - a personal satisfaction. The casual won't be bothered that he won't get his black proto Saab. He is also likely to be killed by an unattentive driver when making a left turn on his way from the store.

The moderate:
The moderate spend his mornings and afternoon in his car en route home or to the office. He drives often and fast, but not too fast. He likes to wear a seatbelt and will if he sees an opporunity to do so. He also experience mild peer pressure when car-pooling.

The hard core:
The hard core has done em all. He dries as fast as he can and as often as he can. Wearing seatbelts is part of his daily routine. He will gladly show off to his peers wearing not only regular seatbelts, but fancy 5-point belts. The ones you can only find together with really epic mounts. WROOM!

... I might've gotten a bit carried away there. :)