The organisations said the findings of the Commons Environmental Audit Committee report on Vehicle Excise Duty were "out of touch" and "beyond belief".
The report states that there is "nothing intrinsically unfair or unusual about setting new VED rates for cars that have already been purchased".
Sheila Rainger, RAC Foundation head of campaigns, said: "It a matter of basic fairness that significant VED changes should only apply to future purchases, not to vehicle choices made up to seven years in the past.
"It is beyond belief that the Treasury introduced these changes without any research into the likely effects on the second-hand market, or a clear understanding of how they would affect low-income households, which already spend a disproportionate amount of their family budgets on transport.
AA members disagree particularly when for some cars the VED will more than double from £210 to £430.
More than 80% of AA members agree that road tax is being used as a stealth tax, according to a recent AA Populus panel of 15,306 members.
AA president, Edmund King, said: "It is intrinsically unfair and unusual to introduce a new system of taxation that applies to families who have already purchased their vehicles and are unable to sell them. This is not sending out a green signal but a mean signal and is penalising many families who cannot afford to change their car."
King has already written to the Chancellor requesting that the "retrospective" nature of VED for cars registered between 2001-2006 should be scrapped.
The study found 70% agreed that having a VED system based on CO2 will influence the type of car purchased.
35% agreed that the new showroom tax will make a difference to the types of cars people buy, however 48% disagreed.