Having a bite to eat while driving can be more dangerous than using a handheld cellphone, a study has found.
The Automobile Association and an insurance company say eating behind the wheel is dangerous and has caused serious injuries and thousands of dollars of damage.
Researchers at the University of Leeds in Britain found reaction times of drivers while eating were up to 44 per cent slower than usual, the Daily Telegraph reported.
Having a drink slowed responses by up to 22 per cent.
A previous study by the British Transport Research Laboratory found alcohol at the legal limit slowed reaction times by 12.5 per cent.
A hands-free phone conversation slowed reaction times by 26.5 per cent.
AA Insurance head of operations Martin Fox said analysis of Kiwi claims showed most crashes were caused by driver distraction.
"Whether it's a cup of coffee, or unwrapping a sandwich or a pie ... anything that means you have to take your eyes off the road is very dangerous.
"We do see some really upsetting accidents, where drivers have unfortunately been distracted and not been able to slow down and a collision has occurred, and those are some very bad accidents."
An AA Insurance survey of motorists in January found eating while driving was ranked the 8th biggest distraction behind the wheel.
One incident involved a driver who drove into a parked car while bending over to stop food falling in the car, resulting in a $10,310 claim.
Mr Fox said people tended to relax in their cars, and many had no concerns with activities such as eating while traffic was moving smoothly.
"But accidents occur, something out of the ordinary happens, and you simply cannot respond. And I think that's the message."
AA motoring affairs manager Mike Noon said although using a handheld phone was not allowed, it would not be realistic to ban eating.
"It comes down to a level of judgment, and a level of appropriateness. It might be okay to eat an apple, it might be okay to smoke a cigarette, but it wouldn't be okay to roll a cigarette while driving.
"What you should be doing when you're driving is driving."
* 44 per cent slower reactions while eating
* 26.5 per cent slower reactions using a hands-free phone
* 22 per cent slower reactions if consuming a soft drink
* 12.5 per cent slower reactions having drunk the legal limit