The study, published online in the British Medical Journal, also said a higher limit could increase gas emissions and air pollution as well as lead to obesity, with more people taking advantage of shorter car journeys.
The authors said that higher speed limits introduced in the United States in 1995 resulted in a 16.6% increase in deaths due to vehicle accidents.
The authors said: "It is difficult to see how any benefits of an 80mph speed limit would outweigh the costs.
"Past evidence shows that speed limit increases lead to substantial rises in road deaths, as well as other potential negative health and economic impacts."
The authors said the proposal appeared to be a "populist gimmick" by the Government.
Given the recent seven-death crash on the M5, they challenged the Government to produce the evidence to justify its policy "with its attendant risks to life".
