New smoking-and-driving rules are not fully understood by the public and little effort is being made to comply with them, a motoring group claimed.
Confused employees are still driving and smoking in spite of changes in the law covering drivers at work introduced in July, said GEM Motoring Assist (formerly the Guild of Experienced Motorists).
GEM also revealed that a poll it conducted showed that 72% of people want a total ban on smoking in vehicles, whether they are being driven for work purposes or not. The organisation expressed concerns at the way cigarettes are disposed of by road users.
David Williams of GEM said: "Employers and even voluntary organisations have a duty to ensure that anyone using a vehicle understands the regulations and that the vehicles have proper no-smoking signs.
"It is the legal responsibility of anyone who drives, manages or is responsible for order and safety on vehicles to prevent people from smoking. If they do not apply this law, they could be liable for a court-awarded fine of up to £2,500."
He continued: "People are beginning to understand that driving with a lighted stick in your mouth is not a good idea. Clearly you may not have proper control of the vehicle, especially if you drop the cigarette or try to light it while on the move.
"It has been made clear that drivers can be prosecuted under current law if an incident occurs while they are smoking because they do not have full control of the vehicle."
On cigarette disposal, Mr Williams said: "Throwing them from a window into the path of other traffic, especially cyclists or motorcyclists, is very dangerous and distracting."
