Many of the vehicles driven by farming families will get more expensive to run, thanks to changes in last week’s budget designed to encourage drivers to switch to lower-emission vehicles.

The Chancellor introduced two measures that will penalise the bigger-engined (and often 4×4) vehicles that typically pump out more carbon dioxide.

One is a first-year “road tax” (Vehicle Excise Duty) rate, arriving in 2010, that will range from £115 to £950 depending on a vehicle’s CO2 output. The other is a change in the pricing structure of standard road tax that will favour smaller-engined cars with low CO2 outputs but hit bigger vehicles hard.

The new scheme will divide cars into 13 bands (up from the current seven), ranging from those under 100g/km CO2 output at the bottom of the scale to those above 255 g/km output at the top.

Range Rover

A new £53,550 Range Rover V8 diesel, for instance, producing 295g/km will attract a £950 first-year road tax charge from 2010. Existing models, meanwhile, will pay the standard rate of £400 this year, rising to £455 in 2010.

Panda 4×4

At the other end of the scale, a new £9660 Panda 4×4 (the smallest all-wheel-drive vehicle on the market) will attract a first-year road tax of a more modest £155, while existing models will pay a standard road tax cost of £145 in 2008 and £155 in 2010.

Pick-up trucks come into the light goods category and now pay £180/year road tax, irrespective of the vehicle’s CO2 output.

These new rates apply only to cars registered after 1 March, 2001. If your car is older than that you’ll pay £120/year if the engine size is below 1549cc and £185/year if it’s above.

Fuel prices

Despite the Chancellor’s decision to postpone his threatened 2p/litre fuel duty rise, farming families are also grappling with rising fuel prices.

Someone driving 12,000 miles a year in a diesel Land Rover Discovery, for instance, and getting 30mpg, would have spent £1454 on fuel in March 2004, £1690 in March 2007 and £2072 in March 2008.

So how will some of the typical cars run by farming families fare under the new system? Here’s a snapshot.