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Honest John: why can I smell petrol fumes when I start my Mercedes?

Flags with the logo of German car brand Mercedes-Benz by car maker Daimler AG are pictured on July 24, 2017 in Stuttgart, southern Germany. Consumer advisors expect a wave of lawsuits in connection with a possible collusion among industry rivals on emissions from their diesel engines. German Der Spiegel magazine had reported Friday, July 21, 2017 that German carmakers Volkswagen, Audi, Porsche, BMW and Daimler had secretly worked together from the 1990s onwards on issues including polluting emissions from diesel vehicles. / AFP PHOTO / dpa / Marijan Murat / Germany OUTMARIJAN MURAT/AFP/Getty Images
Three-pointed stir: a Mercedes dealer should be aware of this common problem with the C-class Credit: MARIJAN MURAT/DPA

If your car has developed a fault, or for consumer advice, turn to Honest John by emailing [email protected]

Filter tips

I purchased my Mercedes C200 new in March 2016 and have recently been aware of petrol fumes, mostly inside the cabin on starting. The car had its last service with Mercedes in March, just before the warranty expired. I rang the dealership in April to report the smell and was told there would be a diagnostic fee of £165. I did not book it in but instead took the car to our local garage, which conducted a check for £33 but could find no problem. What could be causing the fumes? GW

It’s a well-known fault with the W205 C-class. The cause is a blocked carbon filter in the fuel tank breathing system. Because your car is only just out of warranty and because the dealership should already know the cause, they should fix it free of charge without any diagnosis fee.

Malice, a forecourt

You have historically cautioned about car dealers who appear to be legitimate, but in fact have no assets to their name. Is there is a way to detect and avoid such operators? TS

Gut feeling is the most reliable method. If you see a car for sale at the side of the road, run a mile. If the guy is dealing from home, ask for proof that he owns the home (or owns most of it on a mortgage). A franchised dealership should mostly be OK, but if it is owned by a limited company, make a check at Companies House.

Manual dexterity

My daughter turns 17 in October. Should she learn to drive in a car with an automatic gearbox (given that most cars these days are automatic), or is it still worth the hassle of learning to drive a manual? Also, we live in London and would like to buy a second car that she can drive when she passes her test. What do you think? EH

In 10 years, 80 per cent of all new cars will have automatic gearboxes. If she learns in a manual, however, she at least learns skills and a degree of mechanical sympathy. I’d go for the latest Kia Picanto 1.0 (which is manual) and, without being powerful, is fun to drive.

Down to a T

I am just over 5ft tall and recently moved to the countryside. I need a petrol vehicle, preferably used, with a high seating position to help me see over hedgerows – it can be scary encountering strange agricultural machinery and assorted farm animals. What should I consider? AG

Go for the new, short and tall VW T-Cross, all versions of which have height-adjustable driver and front passenger seats. At least one reader has reported a supply problem with 1.0 TSI 95 DSG versions.

Cat might be dog

I have a Jaguar XJ8, which is in great condition and I enjoy driving it immensely. My everyday car is a trusted Rover 75 Tourer Connoisseur SE diesel auto. It never fails and has just clocked 123,000 miles. I’m minded to get rid of both and get a very good used X-Type estate. Does this make sense and, if so, which model should I go for? MSP

Not really. The Rover already enjoys some “classic” status. While the X-type 4WD 3.0 V6 is a good car, the drivetrain could be wearing and it’s not as retro as the Rover. I wouldn’t bother with the 2WD X-type diesel, especially a later one with a DPF.

Touring scars

Does BMW's 2.0-litre, four-cylinder diesel engine have a chain-driven camshaft or a potentially more frail belt?

I have a 2013 BMW 520d M-Sport Touring, with 77,000 miles. I had always assumed that BMW diesel engines had chain-driven cams. I know that my previous 530d certainly had, but a friend told me that the 2.0-litre unit has a belt-driven cam, which requires changing at 100,000 miles. Is this the case? SL

No, but the N47 engine in your car has the timing chain at the rear of the block and is prone to tensioner and timing chain wear, so careful checking and replacement is advised.

Plain speaking

Which ordinary cars (not Mercedes, Jaguar etc) are available with  proper torque converter automatic gearboxes? JW

All new Suzukis except the Celario, all new Peugeots and Citroëns except the 108 and C1, all Mazdas, new Ford Fiesta, new Focus, S-Max, Galaxy and Mondeo petrol models from 2015, most Vauxhalls except Corsa Easytronic.

Beef? Jerky

In March I purchased a 30,000-mile 2016 Skoda Fabia 1.2 TSI SE DSG estate from a dealer. I soon realised that the gearbox was not functioning as it should. It was jerky, particularly in the lower gears when pulling uphill. The garage reset the clutch plates and changed the gearbox oil. Operation is now smooth and much improved, but some rumbling persists. I cannot be sure, but believe this emanates from the transmission. The garage says it’s not serious. Should I be concerned? GC

Yes. This is the VW Group’s DQ200 seven-speed dry-clutch DSG that has caused a lot of trouble. Hats off to the dealer for the quick fix, and for changing the transmission oil (not easy with the DQ200), but there could be further problems around the corner.

Another fine mesh

The Toyota/Lexus hybrid powertrain is capable of huge mileages

I have a mechanical engineering degree and, when replacing my 14-year-old Honda Legend, selected a Lexus GS300h saloon. I was intrigued by the nature of the automatic gearbox and discovered that the whole powertrain is always in constant mesh with not a single clutch involved. It seems to me that, from first principles, such a design ought to be capable of many hundreds of thousands of trouble-free miles: more than any of the belt CVTs or conventional torque converter gearboxes. Does your experience bear this out? AH

Definitely. I have never heard of transmission failure in a Toyota/Lexus hybrid, some of which have more than 400,000 miles under their wheels. One of the coolant pumps is usually the first failure on these cars.

Till diff do us part

I have a 2013 Honda CR-V petrol and have noticed a creaking noise when setting off. This seems to be linked to releasing the clutch, but can sometimes be heard when accelerating from very low speed with the clutch already fully engaged. It sounds like the noise is coming from the rear and I initially thought it was from the suspension, but I can’t replicate it when stationary. Can you help? SA

Yes. It’s a known problem on CR-Vs of all ages. Moisture gets into the rear diff and the fluid needs to be changed.

Golf coarse

We have a 2013 VW Golf 1.4 TSI and it has always been an uncomfortable ride for passengers. It has done less than 25,000 miles and at our recent annual service we were advised that the shock absorbers were “slightly misty”. They can be replaced for £650. Would this substantially improve the ride and is the price extortionate? AM

It’s common and another example of the quality of “hidden” components in VW Group products. Failing dampers will produce a bouncy ride because they are unable to damp the effect of the suspension springs. If VW will not replace them under warranty, or at least offer a generous discount to replace them, seek quality aftermarket replacements.

Case dismissed

What on earth has space for luggage and a large baby buggy, but doesn't cost the earth to buy and run? Credit: Andrew Crowley

I need an automatic petrol five-seat car with a boot large enough to take two suitcases and/or a big baby buggy (with the rear seats occupied). I don’t want a large family car. Any ideas? CT

Look at the Citroën C3 Aircross 1.2 Puretech EAT6.

Idle wise

I recently purchased an MG ZS, which has a turbo. It also has stop/start technology. How does this equate with your oft repeated and excellent advice to let the turbo idle for a while before switching off? RLS

The technology is sufficiently sophisticated not to stop the engine if the turbo is too hot. It also helps if you pull up at a service area or for any other reason. If the stop/start does not switch the engine off automatically, leave it running for a minute or two.

Dash can

Regarding Ford Focus instrument panel issues, I had a similar problem with a 2012 model. The solution was to take out the instrument head unit, spray the back with WD40, gently brush it with an old toothbrush, wipe clean and replace. I found this on YouTube. RM 

Thank you. Yet another use for WD40...

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