Travel in the age of the cart was more dangerous than travel in the age of the car.
Do you think that current numbers of traffic deaths would be higher if we had same age distribution as old England? After all falling from a cart isn't as fatal for an adult as for a kid.
does it change if air pollution deaths are factored in (or estimated, given that https://www.ons.gov.uk/aboutus/transparencyandgovernance/freedomofinformationfoi/deathsinlondonduetopoorairquality says "It is unusual for wider contextual factors such as exposure to pollution or air quality to be recorded among the causes of death")?
While obviously far from exclusively from cars/engines, https://www.gov.uk/government/publications/air-pollution-applying-all-our-health/air-pollution-applying-all-our-health linked from ONS says "poor air quality is the largest environmental risk to public health in the UK" and estimates that it has an annual effect of between 28,000-36,000 deaths. It goes on to say that "The main sources of man-made particulate matter are the combustion of fuels (by vehicles, industry and domestic properties) and other physical processes such as tyre and brake wear" and that "80% of NOx emissions in areas where the UK is exceeding NO2 limits are due to transport, with the largest source being emissions from diesel light duty vehicles (cars and vans)"
Another linked paper (https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/734799/COMEAP_NO2_Report.pdf which I only skimmed until I found a cool quote) says, in the cool quote on p17 that "For a reduction in all traffic-related pollutants, consistent with a 1 μg/m3 reduction of NO2, about 1.6 million life years could be saved in the UK over the next 106 years, associated with an increase in life expectancy of around 8 days"
Then again, maybe breathing in horse farts has a comparable long-term effect? :)