Car clinic: beating rising cost of insurance, curing a damp car and cleaning a diesel particulate filter

Sunday Times Car Clinic experts Emma Smith, Tim Shallcross and Dave Pollard help readers with their car-related problems

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The car clinic experts

Tim Shallcross used to train AA patrols to fix cars. Now he advises the Institute of Advanced Motorists.

Dave Pollard has written several Haynes manuals and has tested just about every car-related accessory.

Emma Smith is a journalist specialising in consumer issues and is a regular Driving contributor


Q. A bottle of water has leaked under the front passenger seat of my Ford Focus. I have tried to dry out the wet patch using a fan heater, but with no luck. It is  now causing condensation to form on the inside of the windscreen. What can I do next? 

BJ, London

A. The simplest solution is to have the air-conditioning system on when you drive. This doesn’t mean you have to be cold, as at any temperature setting air-conditioning dehumidifies a car’s interior very effectively, so it shouldn’t take long to dry out the carpet.

If your car doesn’t have air-conditioning, you could use a wet-and-dry vacuum cleaner to suck the moisture from the carpet, but you may need to unbolt the front seat from the floor to gain proper access and to ensure you get all the water out. If you don’t have such a cleaner you can hire one from a tool-hire firm such as for about £50 a day.

If all this sounds like a lot of bother for some spilt water, bear in mind that window condensation may not be your only worry. Persistent damp could also rot the carpet and corrode the floor.



Q. My car insurance is about to expire and my new premium will be more expensive. All my details remain the same and I have made no claims in the past 12 months. So why am I paying more, and what can I do about it?

BG, Cambridge

A. Premiums actually fell in 2013 by an average of 9%, according to the Association of British Insurers, in response to reforms instituted by the Ministry of Justice last April to crack down on fraudulent personal injury claims. By the last quarter of the year they were beginning to edge up again (increasing 1.4% on average over the period), but a spokesman for AA Insurance said he would still have expected your annual premium — on a like-for-like basis — to have fallen.

All insurers calculate risk in slightly different ways and sometimes change their assessments from one year to the next, based on analysis of claims. This could have resulted in the increase. Or perhaps the rise is due to a change in your circumstances that you have not considered — a rise in the number of claims in your area, for example, or your entering a new age bracket. If you had an accident, even if it was not your fault, this too could increase your premium.

However, the most likely reason for the rise, somewhat perversely, is your loyalty. Insurers often use competitive quotes to lure new customers. This helps to drive down the average premium and mask small rises in the rates they charge existing customers.

Our advice is to shop around. Go to price comparison websites such and, and look for better quotes.

Some big insurers, including Direct Line ( and Aviva ( , do not appear on comparison sites, so approach them directly.

You can now choose to accept a cheaper quote or, if you’d prefer, to stick with your original insurer, go back to it with your new quotes and try to negotiate a better deal.

According to the AA, shopping around in this manner can save motorists, more than £300 on average on their annual car insurance. Just be absolutely certain that you are comparing like for like insurance rather than scrimping on your level of cover.



Q. When we bought our one-year-old diesel Volvo XC60 we were unaware of the vagaries of its diesel particulate filter (DPF). I work away from home a lot and leave the car with my wife, who drives only short distances and does not like motorways. Within a week of leaving the car with her, the DPF warning light came on. How long should it take the filter to fill up with soot? And when I take the car for a motorway run, how can I tell when regeneration has occurred? 

TL, Liverpool

A. A good dealer should check that the car you are buying is a good match to your lifestyle. Almost all new diesel cars sold since 2009 are DPF-equipped, as this allows them to meet the stringent Euro 5 emissions standard  that came into force that year. And many diesels were fitted with one before this in anticipation of the legislation.

Since February DPFs are checked as part of the MoT, and any car that has had one removed will automatically fail the test.

The DPF collects soot entrained in the exhaust gases, and it is almost impossible to predict how long it will take one to fill up, as this depends on the driving style and typical journey type, the quality of both fuel and engine oil and even the ambient temperature. In the worst case it could take as little as a week to become obstructed, although that isn’t likely.

DPF “regeneration” is the process of getting the exhaust gas hot enough for long enough to burn off the collected soot. In most cases it happens automatically, either because the car has sufficient high-speed use or because the engine management “knows” soot has built up and so increases exhaust-gas temperature by altering engine-running characteristics for a while.

If journeys are too short or too stop-start, however, regeneration might not complete and the warning light will come on, so action needs to be taken. This generally involves taking the car for a motorway run of at least 20 minutes’ duration with the engine  kept above 2500rpm (by using a gear lower than normal).

There is no obvious way to tell if regeneration is taking place. The most drivers will see is the occasional slight puff of exhaust smoke as soot burns off. If the problem persists, consider changing to a petrol car.