Raising the speed limit on motorways is likely to lead to more crashes, as well as environmental and personal health concerns, experts say.
The British Medical Journal report indicates that the economic benefits of increasing the speed limit from 70mph to 80mph, currently being considered by the Government, are outweighed by the safety risk.
Any increase in accidents could see the number of car insurance claims rise, possibly impacting on future premiums.
Researchers from the London School of Hygiene and Medicine found that when higher speed limits were introduced in the past, this led to more vehicle accidents. In the US in 1995, a rise in the speed limit resulted in 16.6% increase in road fatalities.
They are also concerned that increased gas emissions and air pollution may result from a higher limit.
The reports authors said: "It is difficult to see how any benefits of an 80mph speed limit would outweigh the costs."
They called the proposal to increase the speed limit a "populist gimmick" by the Government. Following the recent M5 pile up that killed seven people, the authors are challenging the Government to provide some sort of evidence to back its proposal.
© Press Association 2012