Pay-As-You-Drive?

There is a proposal for Pay-As-You-Drive car insurance. Your insurance rate is per-mile, not per-6-month-term. This would decrease insurance rates of those who drive little (like yours truly) but raise them for those who drive long distances. It would of course motivate decreased driving, which is a good thing from the point of view of emissions, congestion, road maintenance, vehicle maintenance, etc. I support the idea, since it seems to cause more of the cost of an activity (driving) to be borne by those participating in the activity (drivers).

However, part of the rationale used in the proposal is rests on the assumption that people who drive more get into more accidents. This deserves consideration. Stated flatly like that I have no doubt it is true: the more you drive, the more exposure to the risk of driving you undergo, thus more accidents for longer drives. However, it's also possible/likely that people who drive a lot are, by virtue of larger experience, better drivers than those who drive very little. Additionally, people who drive the longest distances tend to do so on cross-country highways, not in cities. The risks of highway driving are different from stop-and-go city traffic.

So, while long drivers are likely responsible for more total accidents than short drivers, their rate of accidents per mile may be less. I suppose that this could be taken into account by insurance companies by charging a higher rate for the first 5 or 10 thousand miles driven, then gradually decreasing the per-mile rate up to a certain point thereafter.