One in seven fleet drivers eat a meal while driving at least once a week, putting themselves and other drivers at risk.
Research by road safety charity Brake has found those driving for work are far more likely to munch on the move, with only one in 25 of other drivers admitting to a eating behind the wheel.
The results suggest that at-work drivers are more likely to try and multitask when on the roads, and Brake is urging firms to ensure employees are instructed never to eat while at the controls of a vehicle.
The practice can have a significant impact on reaction times.
Research carried out by Fleet News in 2005 suggests that even eating a bag of crisps can delay a driver’s reactions by as much as 20%.
Even if no crash occurs, the consequences of eating behind the wheel can be severe.
In June last year a Dutch lorry driver was jailed for eight weeks and banned from driving for a year after being spotted eating a plate of spaghetti while driving erratically on a Welsh dual carriageway.
Brake has called for more traffic policing to target those eating on the move.
“Crazy multi-tasking while driving causes deaths and injuries,” said head of campaigns Cathy Keeler.
“Drivers must plan regular breaks on long journeys to allow time to eat, as well as to ensure they aren’t driving tired.
"Driving is the most dangerous activity that most of us do on a daily basis.
"No-one would dream of snacking on a sarnie while using a chain saw or doing any other safety-critical job – and we mustn’t when driving.
"Using a vehicle as a dining room can also impact residuals."
Simon Henstock, network operations director for auction house BCA added: “We know that used car buyers put presentation very high on their list of considerations when buying a vehicle.
"In case drivers have used their cars as a standby diner, fleet managers should ensure vehicles are properly prepared before remarketing as this could affect the resale value.”