Members of the Association of Car Fleet Operators Annual General Meeting were urged to encourage their drivers to set their speeds to safe levels for road conditions.
Mark McArthur-Christie, road safety spokesman for campaign group the Association of British Drivers, said educating drivers about safe speed was vital.
He told the meeting, held at the Motor Heritage Centre, in Gaydon: 'A village may have a limit of 30mph, but is it safe to travel through that village at that speed? I would suggest 20mph is a safer speed in those conditions.
'Not enough fleets educate their drivers about speeding. They think that if they put their drivers through a driver training programme it will just cost them money. But there is payback in areas like improved fuel consumption and less accidents.'
His comments came as Government figures produced last week show that 58% of motorists exceeded 30mph speed limits last year, with 25% travelling faster than 35mph.
On 40mph roads, 27% of cars exceeded the limit, with 10% exceeding 45mph, the study found.
A total of 57% of motorists exceeded motorway speed limits, with the number travelling faster than 80mph rising slightly, from about 18% between 1998 and 2002 to 20% in 2003.
It was announced last week that the Government plans to change penalties for motorists committing minor speeding offences.
It is believed the Government will award two points to drivers travelling at one or two miles per hour over the limit, with the number of points awarded increasing for faster drivers.
In response, McArthur-Christie said: 'A driver travelling at 45mph on an empty road at 2am could be causing far less danger than one doing 35mph at a busy time, perhaps past a school or a shopping area, yet under these new proposals the former driver will be severely punished while the latter will have his penalty reduced.'
Government figures announced in a Parliamentary answer reveal that where vehicle activated signs are used to warn drivers of a speed limit there has been a 31% reduction in accidents.