The popular 2-litre diesel – the Ford Focus TDCi – emits 148g/km of CO2, which means a current annual bill of £120

Chancellor Alistair Darling announced the Budget 2008 – but what does it mean for motorists with cars registered after 1 March 2001?

Vijay Pattni rounds up the essential information for owners of the UK’s best-selling motors.

View our slide show of the UK’s best-selling cars

City  ¦ Supermini ¦ Hatchback ¦ Family ¦ Executive ¦ SUV

City 

Ford Ka

It’s twelve years old, featured Kylie Minogue in its advertising campaign and is one of the UK’s best selling city cars.

The standard 1.3-litre Ford Ka emits between 154g/km of CO2 – meaning a current annual bill of £145.

From April 2009 you’ll pay £150 for your Ka, and if you buy a new Ka in 2010 you’ll pay £155.

Toyota Aygo

The cutesy budget motor shares its components with the Citroen C1 and Peugeot 107 – and its 1-litre petrol engine emits just 109g/km of CO2. You’ll currently pay £35 annual road tax.

But from April 2009, you’ll save £10, paying just £20 a year – buy a new Toyota Aygo in 2010-11 and your first year road tax is free, followed by a £20 annual bill.

Supermini

Mini

BMW’s take on the iconic Mini has captured the nation’s heart – it is one of the most popular and sought after small cars, offering up a great drive and excellent build quality.

The Mini 1.6-litre petrol emits 139g/km of CO2, meaning an annual bill of £120. This drops to £110 from April 2009, but goes up to £115 under the new rules in 2010-11.

And the 1.6-litre diesel model (118g/km) which currently has a £35 annual bill saves a fiver from April 2009, dropping to £30. And buy a Mini Cooper diesel in 2010-11 and your first year road tax is free, followed by annual payments of £35.

Ford Fiesta

The humble Fiesta has seen over thirty year’s worth of British motoring – and remains one of the best superminis on sale today.

The 1.4-litre petrol-engined Ford Fiesta – which emits 147g/km of CO2 – costs £120 a year to tax – this will stay unchanged until the new rules in 2010-11, when the annual bill rises to £125 a year.

Hatchback

Ford Focus

The UK’s best-selling car since it was launched in 1998 blends outstanding handling and genuine practicality.

The popular 2-litre diesel – the Ford Focus TDCi – emits 148g/km of CO2, which means a current annual bill of £120. Buy a new diesel Focus in 2010-11, and you’ll pay £125 a year.

Volkswagen Golf

The people’s car is back – the new generation Volkswagen Golf has re-established the premium hatch which doesn’t cost a premium.

The petrol-powered 1.4-litre FSI engine emits 149g/km of carbon – meaning an annual bill of £120. This stays the same until 2010-11, rising to £125. The 2-litre diesel model currently costs £145, rising to £150 next year, and £155 on new Golfs from 2010-11.

View our slide show of the UK’s best-selling cars

Family

BMW 3 Series

The previous generation BMW 3 Series famously sold more units than the equivalent Ford Mondeo – Brits love the badge, build quality and unparalleled handling for a car in this class.

The most popular 3 Series – the diesel 320d – emits 128g/km of CO2, which costs £120 a year. This drops to £90 from April 2009, and buy a new 320d in 2010-11, and the first year of road tax is free, followed by an annual bill of £95.

Ford Mondeo

While the baby Beemer may have swept up the previous model's sales, there is no discounting the quality of the new Ford Mondeo, which looks to take the fight straight to the new 3 Series.

The 2-litre TDCi (diesel) model Mondeo emits 156g/km which currently costs £145 a year, rising to £150 next year, and £155 from 2010-11. If you own the hot 2.5-litre petrol engine version – with 222g/km of CO2 emissions – you’ll pay £210 a year, rising to £300 next year. Buy a 2.5-litre Mondeo in 2010-11 and you’ll pay the first-year ‘showroom tax’ of £550, followed by an annual £310 bill.

Executive

BMW 5 Series

The previous generation BMW 5 Series was once voted the best car in the world, and the new model has picked up the baton where the old one left off.

Opt for a 2.5-litre diesel BMW 5 Series (165g/km) and you’ll pay £145 a year now, and £175 next year. Buy one in 2010-11 and you’ll pay the so-called ‘showroom tax’ of £250 for the first year, and £180 a year after.

Audi A6

Audi has come a long way – and the new A6 is testament to the company’s new face, with solid build quality, excellent driving dynamics and the crucial understated appearance.

The 3-litre diesel Audi A6 (211g/km) costs £210 to tax, which rises to £300 next year. Under new rules, buy a new 3-litre diesel A6 in 2010-11 and you’ll pay the first-year rate of £550, followed by a £310 annual tax bill.

SUV

Land Rover Discovery

A practical family car, great off-roader and entertaining through the tight twisty tarmac, the Land Rover Discovery is all things to all people.

The 2.7-litre V6 diesel in the Disco emits £249g/km – meaning an annual bill of £400, rising to £415 from April 2009.

But buy a Discovery in 2010-11, and you’ll pay a first year road tax bill of £750, followed by a £430 annual bill.

Volvo XC90

The sturdy Volvo XC90 is one of the great SUVs, offering up outstanding practicality and economy for a car in this class, coupled to good on-road behaviour.

The Volvo XC90 2.4-litre diesel emits 219g/km of CO2 – which means £210 a year now, and £300 from next April. Buy a XC90 in 2010-11, and you’ll pay the first year ‘showroom tax’ of £550, followed by annual payments of £310.

View our slide show of the UK’s best-selling cars