The scheme is only expected to apply to new cars, which do not need an MOT certificate, and a price has yet to be worked out.
At the moment, a 12-month disc costs £165.
Tony Leigh, chairman of the Association of Car Fleet Operators (ACFO), said he felt the success of the idea would hinge on whether a discount would be offered for buying a three-year disc, thus justifying the higher initial outlay.
He said: ‘Administratively, it would save a bit of time and trouble, but you’d only be talking about vehicles that you’re going to keep for three years.
‘For the larger fleets, it would be more of a hassle to work out what’s going to be kept for three years or not.’
Leigh said many sectors would not be interested, such as rental firms that do not keep vehicles for three years, and manufacturers that run demonstration cars.
But he added: ‘It’s an interesting idea that should be opened for discussion.’
A spokesman for 170,000 vehicle-strong Lex Vehicle Leasing, the UK’s largest leasing company according to the FN50, said: ‘This would be a sheer pleasure. The administrative paper chase involved in doing this every year can be incredibly frustrating.’
But a Confederation for British Industry spokesman said: ‘I cannot imagine too many businesses digging deep into their pockets to shell out for three years of road tax when they can continue to buy the tax discs on a yearly basis and conserve their funds.’
However, a Department for Transport spokesman claimed: ‘It’s just an idea that’s being looked at. They have identified the potential benefits to fleet users but it’s very much an embryonic idea. They’re looking at it along with many other things.’