Some 44% of motorists fear the scrapping of the paper tax disc will encourage people to break the law, according to the RAC.
From 1 October, it won't be necessary to display a paper disc on your windscreen, with the DVLA moving to an electronic registration system that will allow drivers to pay their car tax via direct debit.
Nearly two-thirds of motorists also fear the change will lead to a rise in the number of untaxed cars on the road.
RAC chief engineer David Bizley said: "There is clearly concern among those motorists that we surveyed over the issue of enforcement. Most of the changes make sense and will benefit the motorist, but too many motorists are unaware of the detail and the big question has to be whether enforcement using only cameras and automatic number plate recognition will be sufficiently effective.
"There are clearly many people who still believe that the humble tax disc is a simple yet highly effective way of ensuring all motorists pay their VED. As a result, there is real concern that without the need to display a disc, less scrupulous motorists will take a chance and try to evade payment.
"This already happens with insurance and adds an average of £33 to the premiums of the law-abiding majority who pay their insurance."
However, the DVLA disagreed with the RAC. A spokesman said: “It is nonsense to suggest that getting rid of the tax disc will lead to an increase in vehicle tax evasion. We have a proven track record in making vehicle tax easy to pay but hard to avoid, with over 99% of all vehicles taxed. The DVLA and the police have been using cameras and automatic number plate recognition for enforcement since 2001, with car tax evasion being halved from 1.5% in 2007 to 0.6% in 2013.”
Meanwhile, more than a third of motorists aren't aware that the paper tax disc is about to be made obsolete.
With less than two weeks to go before its demise, the RAC found that 36% of drivers didn't know anything about the changes, while 47% of drivers were uncertain when the changes were coming into force.
Such changes include from 1 November direct debits will be available and motorists will be able to pay their tax on an annual, six-monthly, or monthly basis.
Here is what you need to know about the scrapping of the paper tax disc.
Buying a car
From 1 October, the tax on the vehicle you bought will no longer be transferred with the car - you will need to get new tax before you can drive. This can be bought online, on the phone or via the Post Office using the existing 'New Keeper Supplement' part of the vehicle registration certificate.
Selling a car
If you sell a car after 1 October and inform the DVLA, you will automatically be refunded for any full calendar months left on the tax that are unused. You will no longer need to make a separate application for a refund of vehicle tax.
When direct debits won't be available
You won't be able to tax your vehicle via direct debit for fleet schemes, HGVs or first-registration vehicles.
How to check the tax status of a vehicle
You can check the status of any vehicle by visiting gov.uk/check-vehicle-tax