[SAJ]

The effect of ''group speed'', as you put it, is an enormously complex calculation, if such it can be called. The problem really requires a model, not a calc, and, as with all models, results will depend on the underlying assumptions (can you say 'global warming'? I knew ya could...g!).

To adjust the formula I gave for the present value of the death of a motorist to include deaths to other parties, all that would have to be done is to obtain figures on the number of NON-driver deaths, via motor vehicle, per million miles per annum, then add the appropriate factor. It's a straight proportion, nothing very fancy.

The resulting figure is going to be VERY tiny, tinier than the single-driver calc, so I'm not too worried about omitting it from my post.

[no-s]

yup. i came to the same conclusion, sorry, posting before thinking. Similarly with non-motorist fatalities.