The burden of soaring fuel costs could be eclipsed by plans to raise the difference in road tax bands (vehicle excise duty) to £300.

If implemented, the move would more than double the combined fuel and road tax costs for owners of some of the most popular family cars, in just six years, according to figures from the Society of Motor Manufacturers and Traders.

The changes could mean a charge as much as £1,800 for Band G cars, which were published in the Environmental Audit Committee's Reducing Carbon Emissions from Transport report and have been promoted by some as an anti-4x4 measure.

The SMMT chose two cars in each of the current road tax bands for the analysis. Researchers took August 2006 as the base and tracked back to 2003; they then analysed the position in 2009, on the assumption that VED changes had been made.

Christopher Macgowan, SMMT chief executive, said: "Our analysis shows that changes to road tax would hit drivers of small and family cars in a tax double-whammy, firstly through fuel costs and secondly road tax. It would add more pain to families struggling with rising energy costs at home and threatens to further dampen consumer spending."

Increase in motoring costs by model - fuel and road tax, 2003 - 2009

VED band Model 2003 2006 2009* Six year increase Percentage increase
B Nissan Micra 1.5 diesel £766 £873 £1,181 £415 54.1%
B Vauxhall Corsa 1.0 petrol £782 £875 £1,211 £429 54.9%
C Ford Focus 1.6 diesel £821 £963 £1,503 £682 84.3%
C Renault Modus 1.2 petrol £973 £1,125 £1,718 £745 76.6%
D VW Golf 1.4 petrol £1,081 £1,254 £2,131 £1050 97.1%
D Toyota Corolla 1.4 petrol £1,110 £1,288 £2,169 £1059 95.4%
E Vauxhall Zafira 1.9 diesel £1,088 £1,287 £2,402 £1314 120.8%
E Peugeot 307 1.6 petrol £1,236 £1,439 £2,606 £1370 110.8%
F Volvo S40 2.4 petrol £1,412 £1,669 £3,114 £1702 120.5%
F Honda Accord Tourer 2.0 petrol £1,427 £1,689 £3,133 £1706 119.6%
G BMW 5 Series 2.5 petrol £1,541 £1,856 £3,579 £2038 132.2%
G SEAT Alhambra 2.0 petrol £1,588 £1,912 £3,640 £2052 129.2%

(* 2009 figure assumes introduction of Sustainable Development Commission proposal, quoted in Environmental Audit Committee report, to increase road tax, differentiating each band by £300, rising to £1,800 for G band.)