One in five drivers clueless on drink limits SCOTS drivers are clueless about the drink-drive limit with a fifth admitting they have no idea how many units are in any alcoholic drink. Drink driving is on the increase and many motorists are putting themselves and other road users at risk because of their lack of knowledge about the alcohol content of popular drinks, according to the latest research. The study is being read as a timely warning of the dangers of the festive party season as police forces say that December is the month most drivers are caught under the influence of alcohol. According to a report, Strathclyde Police arrest more drunk drivers than any other force in Britain, with the exception of Manchester and Hampshire. The report from LV= car insurance reveals the number of motorists confessing to driving while under the influence of alcohol has almost doubled since 2009. One in six (15 per cent) of more than 2,000 drivers surveyed admitted that they have driven while over the legal alcohol limit at some point, despite the fact that the majority (88 per cent) of these acknowledge it affects their ability to drive. But this upward trend in drink driving is being exacerbated by widespread confusion about the number of alcohol units in popular pub drinks. One in five (20 per cent) drivers cannot name the correct number of units in any alcoholic drink with a pint of lager the most frequently underestimated - with four out of five (80 per cent) drivers thinking it has fewer units than it actually does. There is also widespread confusion over the alcoholic content of wine, with the majority of motorists getting its alcoholic content wrong too. More than half (55 per cent) of motorists underestimate the number of units in a large 250ml glass of wine - believing it only has two units of alcohol or less. It contains three. As well as not knowing how much alcohol a drink contains, a significant number of motorists have no idea how much they can consume before they would be over the legal limit to drive. The law states that a driver can have a maximum of 80mg of alcohol per 100ml of blood, 35mg per 100ml of breath or 107mg per 100ml of urine. This equates to approximately four units for an average man and two to three units for an average woman - yet only a third (34 per cent) of drivers could correctly say what the legal limits were. However, as alcohol tolerance depends on a number of factors including the person's age, weight, gender and metabolism, the only way to be certain of being under the limit is to completely abstain from alcohol before driving. In the run up to Christmas, drink driving arrests peak across the UK. According to official police data, obtained by a Freedom of Information request from LV= car insurance, December is the month in which most drink drivers are caught each year. The data also shows that more drink drivers have been caught by the Greater Manchester Police than anywhere else in the country, making it the drink drive capital of the UK. Greater Manchester Police have caught over 13,056 motorists in the past three years followed by Hampshire Police (7,006 caught) and Strathclyde Police (6,444 caught). According to the police data made available, the UK's drunkest driver was pulled over earlier this year by Cumbria Police, recording a breath test of 238mg of alcohol per 100ml of breath.