Some two million British drivers have admitted to getting behind the wheel because they were "less drunk" than their passengers.
Some 7% of Direct Line motor insurance customers admitted to drink-driving in the past two years with passengers in their car, with 80% of them stating it was because they were the most sober of their party.
Among the 'most-sober drivers', 44% admitted that it happened on a regular basis, while more than a third (35%) said they had done it more than once.
Asked why they took such a risk, nearly a third (29%) said they thought it was a good idea at the time, the same amount thought they were less likely to be involved in an accident if they were driving rather than their friends, while a worryingly-high fifth (20%) said they did it because they didn't think they would get caught.
The most common reasons why drivers took a chance were returning from: a night out (32%); a dinner or drinks party (25%); a wedding (21%) or a birthday party (21%).
David Davies, executive director of Parliamentary Advisory Council for Transport Safety, said: "Drink-driving kills over 250 people each year so it's concerning that so many motorists are willing to drive when they suspect they might be over the limit.
"This month, drink-drive legislation is being tightened and legal loopholes are being closed, making it easier for police to prosecute drink-drivers. New legislation to counter drug-driving has also come into effect across Great Britain so if you drive under the influence of alcohol or drugs, the penalties will be much higher."
Rob Miles, director of motor at Direct Line Car Insurance, said: "Being less intoxicated than the rest of your party isn't a reason to drive. If you are over the limit and get caught or have an accident, being the least drunk out of your group does not mean the penalty or the danger will be any less. We'd encourage all drivers to avoid alcohol altogether if they intend to get behind the wheel."