Q Has the government’s plan to increase road tax for cars registered before 2006 been ditched in the wake of last week’s pre-budget announcement? I own an Alfa Romeo Spider 3 litre 24v dating from 2006 and am worried that the tax could double from £210 per year. — TM from Appin, Argyll

A Finally, a spot of good news for hard-pressed motorists. The government used its pre-budget statement to execute a swift U-turn on car tax — or, more correctly, vehicle excise duty (VED).

The level of VED is determined by the amount of CO2 a car emits, in your case 278g/km. At present, a car that emits more than 225g/km falls into tax band G. This costs £400 a year unless the car was registered from 2001-06, in which case band F applies, at £210 a year. (If the car is pre-2001, the duty would be £185 a year.)

From April there will be 13 (rather than seven) road tax bands. The original proposal was that all cars that emitted more than 255g/km would fall into the new band M, at £405 a year — a hefty increase for you. The pre-budget report reveals, however, that the government will alter the classification of cars registered in 2001-06 so that the tax-band increases for 2009 will be limited to £5 and you will pay a more reasonable £215 next year.

Keep an eye on developments, as there will probably be bigger increases from 2010 onwards. See full details at tinyurl.com/5c5e4j .

The temporary reduction in Vat (from 17.5% to 15% until December 31, 2009) will trim the price of fuel, but it is cancelled out by a 2p per litre boost in fuel duty from tomorrow. There will be further 2p per litre increases in April 2009 and April 2010. Far from a heart-warming prospect, then.

Q I am a high-mileage motorway driver who typically covers 35,000 miles a year. I have been happy with my BMW 320d SE, but as the car is nearly six years old and I have had three turbos replaced, the time has come for a new one. My key requirements are reliability, economy and preferably an unlimited-mileage warranty. — PW from Wiltshire

A In 2001 BMW introduced a three-year unlimited-mileage warranty provided you kept the car serviced to its recommendation. Today several car companies offer the same cover, including Mercedes-Benz, Jaguar and Land Rover. In some cases it is possible to extend a new car’s warranty beyond three years, albeit rarely on an unlimited-mileage basis. If you can’t find suitable cover, try online warranty providers such as www.warrantydirect.co.uk or www.warrantyworks.co.uk . That said, it might prove more economical to self-insure — put aside some money in case the car goes wrong.

If you don’t fancy another BMW or a Mercedes-Benz C-class (its direct competitor), consider the Jaguar XF. This also has an unlimited-mileage warranty and is highly rated for comfort and refinement, something you will appreciate on long motorway runs. Another sound option for you would be the new Honda Accord. The three-year warranty is only for 90,000 miles rather than unlimited, but the car’s 2.2 litre engine is among the cleanest and most economical in this market and Honda has a good reputation for reliability.

Q I own a Jaguar XJ6 Series 1 with a 2.8 litre engine but am struggling to find spare parts so am thinking of selling it. I hope to shift it for £5,000, considering that the engine and the bodywork have both been reconditioned. How likely am I to get this price and do you have any tips? — SB from Fulham, London

A The figure of £5,000 you mention is at the top end of what you could hope to get for a Series 1. In reality, you are more likely to achieve about half that price — and even this assumes that it is in good condition, with receipts for the work you have had done.

To achieve the highest price for such a specialist vehicle, try advertising in a classic car magazine such as Classics Monthly or Practical Classics. It is better to talk to a small but specialised audience than a vast but mostly indifferent one. Consider enthusiasts’ websites too; one of the biggest is www.classiccarsforsale.co.uk .

Join the Jaguar Enthusiasts’ Club (www.jec.org.uk ), which has a regular magazine that carries classified ads.

If you decide to hang on to the car then owners’ clubs usually have a list of spare-parts suppliers, which should make keeping your XJ6 on the road easier.

To get the best price, the car needs to be accurately described, with the correct colour and trim names, and ideally accompanied by at least one colour photo. Always include a specific price and make sure the car is ready for sale. Ideally it should be clean and taxed and have a long MoT, which indicates the car is usable and can be driven away immediately.

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E-mail your questions to carclinic@sunday-times.co.uk. Alternatively, write to Car Clinic, InGear, The Sunday Times, 1 Pennington Street, London E98 1ST. Please supply us with a daytime phone number, the town or city you live in and as much detail about your car as you can. We cannot reply to letters personally, so please do not send original documents or SAEs. Advice is offered without legal responsibility