In 2001 as many people died every 26 days on US roads as died in the terrorist bombings of 9/11, the study shows.
The authors compared the number of deaths from international terrorism and car crashes in the 29 member countries of the Organisation for Economic Cooperation and Development (OECD) between 1994 and 2003.
They used the US State Department Counterterrorism Office database for deaths caused by international terrorist activity, and the OECD International Road Transport Accident Database for 2000 and 2001 for those caused by car crashes.
For the 29 OECD countries, 33 acts of international terrorism occurred during the study period, accounting for 3064 deaths, excluding those of the perpetrators.
The attacks all occurred in 10 of the OECD countries, with the highest number of fatal attacks in Turkey.
The annual death rate from car crashes was around 390 times higher than the death toll from international terrorism.
Among the 10 countries where people had died as a result of international terrorism, the ratio of road deaths to terrorist deaths ranged from 142 times greater in the US to over 55,000 times greater in Poland.
Deaths from car crashes were equivalent to the impact of a 9/11 attack every nine day, for all the countries put together.
The authors cite other evidence, suggesting that the number of Americans who avoided flying after 9/11 and were subsequently killed in car crashes was higher than the total number of passengers who died on the four 9/11 flights.
The authors are at pains not to minimise the emotional, economic, and political impacts of terrorism. But they point out there is a huge difference in the scale of death between terrorism and car crashes. And the evidence to inform policy is also much greater for car crashes.
"Policy makers need to consider these issues when allocating resources towards preventable interventions that can save lives from these two avoidable causes of mortality," they conclude.