You know, for the odd occasion when I am driving arond town (rather than lugging loads of gear/people & towing trailers about the place) I have considered the economics of a second car.
The things that are preventing me from getting a little 1.0l petrol or similar are as follows:
1./ Council actively make it as difficult as possible for me to have a second car, with parking fees for permits etc
2./ The only direct financial benefit I would see would be fuel economy (which would soon add up, as I spend around £375 a month on Diesel), and the environmental benefits are not likely to be noticeable to me (selfish I know).
3./ My landie doesn't bugger the suspension, nor does it ever ground out on the Portsmouth speed humps.
5./ The high driving position gives me great visibility coming up to round abouts, driving around the residential streets etc, and I can usually spot things far earlier and respond to them. This effect is more pronounced in town than on motorways, as generally more is happening.
4./ And I simply can't afford a second car...
And as for being less/more likely to kill someone - I find that not hitting them in the first place is generally a good plan
So, as I bought my Landie to do a small amount of off roading, cope with large amounts of gear, sometimes heavy tows, carry 7 people, and cope with the odd poor qaulity slipway, even though I live in a town, it's staying!