What does concern me is the quality of driving... I'm much more likely to be killed by a drunk or otherwise impaired driver. And I'm sure the road death statistics aren't pretty in the UK either.
I wouldn't be concerned about coming over here for a few days for a conference or whatever.
FYI: Annualised road fatality death rates per 100,000 population - UK 2.9 (world ranking 4th), USA 10.6 (world ranking 60th). And by comparison the best and two worst: Micronesia 1.9, Thailand 36.2, Libya 73.4. (I included the bottom
two because Libya's figures are such an outlier.)
Firearms mortality rates (all causes deliberate and accidental, again per 100,000 population) - UK 0.23, USA 10.54 (no figures for those other three countries).
So, you're right, you should be
marginally more scared of cars than guns. In both countries you're more likely to commit suicide than be killed by a gun or on the roads (7.4/100,000 and 12.6/100,000 respectively) which is a considerably more worrying statistic.