Honest John: should I join Mercedes diesel emissions civil lawsuit?

Our consumer expert advises on whether it's best to go to court or allow Mercedes to sort it. Plus: a little-used Audi costs a lot to repair

Flags with the logo of German car brand Mercedes-Benz
Three-pointed stir: is it worth getting in a flap over NOx emissions? Credit: MARIJAN MURAT/Getty Images

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

Unsolicited solicitor

I received an unsolicited email from a legal firm offering to act on my behalf regarding Mercedes diesel emissions. My car is a 2013 Mercedes C220 CDI AMG Sport Coupé. I know that there has been a scandal over VW emissions, but had not read anything about a similar situation regarding Mercedes. Is it worth following up? RN 

Mercedes has been compelled by the German authorities to recall certain diesel-engined models due to excessive NOx (oxides of nitrogen) emissions. If your car was affected, you should have received notification from Mercedes UK for it to be taken to an authorised dealer for an adjustment. Various legal firms seem to be getting hold of lists of the registered keepers in order to potentially profit from a class action lawsuit, citing that customers were misled about the emissions their vehicles produced. A spokesperson for Mercedes-Benz UK said: “We believe the claims brought forward by the UK law firms are without merit, and will vigorously defend against them or any group action.”

Airing their views

Our 2017 Ford Tourneo Connect’s Continental 205/60 R15 tyres will need replacing soon. We do some long trips and our biggest fear is a puncture on a motorway or very busy road; we have no spare wheel due to an electric wheelchair ramp. Would replacing the tyres with run-flats be a good idea? LK

In the circumstances, switching to run-flats would be very sensible. Options include Bridgestone DriveGuard, Continental SSR, Michelin Zero Pressure (ZP) and Pirelli, which has just launched a range of Cinturato all-season run-flats.

Status quote

Should a five-year-old but low-mileage Audi TT require expensive repairs?

My daughter bought a used Audi TT with a 2.0-litre petrol engine. It is now five years old but has only done 21,400 miles, with few of them in the last four months. It passed a recent MoT, but the dealer reported that the engine thermostat housing was leaking slightly and needed replacement in the near future and also that the clutch pedal mechanism was sticking and needed attention. The quote for repairing the leaking thermostat was £900. It is disappointing that such an expensive and prestigious car has developed these faults after such little use. Is it worth taking this up with Audi? DG

You could ask the Audi dealer who quoted you £900 if Audi itself will contribute. The failure could be due to comparative lack of use. The Audi TT carries status, but the engine is from a VW Golf and is also used by Seat and Skoda. It’s quite good, but there is nothing prestigious about it. A high proportion of reader emails I receive highlight expensive faults and repairs in VW Group cars.

O dear

The battery of my mother’s 2005 Rover 25 automatic keeps going flat. The AA man said it was like a bulb being on permanently. She has run the engine every day as advised to keep the battery charged, but now the red coolant warning light has come on. She added coolant, but the warning light came back on. The amber engine light also now flashes, indicating a fault detected by the engine management system. Any ideas? HA

The battery drain is probably due to a fault with the interior light delay switch remaining live after it has switched off subsequent to exiting the car. Switch the light off completely so it does not come on when you open a door. The cooling problem might be due to failing inlet manifold O-ring gaskets, an Achilles’ heel of the Rover K-series engine. The engine contains very little coolant and, if this runs low, the cylinder head gasket and bore liner seals can fail, effectively scrapping the engine.

Only way in Essex

For safety, there are worse places to be than in a Volvo XC40

I sold my late husband’s Volvo XC60 as I thought it too large for our Essex village roads. Having travelled on the A12 to visit friends, however, I realised that my VW Polo was being “eaten up” by the many container lorries that use this busy route to travel to Harwich. I am now in a dilemma as I feel I need a larger vehicle and want advice from someone other than a salesman. I quite fancy a VW Touran or a Ford EcoSport. What are your views? PM

A Volvo XC40 would solve the problem – and a 200bhp T4 or 250bhp T5 will give you the power to keep away from container lorries. There is merit in buying an SUV (sports-utility vehicle, like the XC40), because you sit higher, see farther and feel safer. You could consider a hybrid version or even a fully electric version of the XC40, but prices now nudge £50,000. A VW Touran is a small MPV (multi-purpose vehicle) with up to seven seats (you might have meant VW Tiguan, which is an SUV). A Ford EcoSport is a smaller SUV, no more powerful than a Polo and not a very good car anyway. VW does an SUV version of the Polo called the T-Cross, which is quite good but no longer than a Polo.

Hard lessen

Might a tyre swap improve a Hyundai Tucson's firm ride?

My wife’s Hyundai Tucson has just had its second service, at 12,500 miles. The dealer said both front tyres are worn and recommended immediate replacement, despite the tread depth being legal. The ride is quite hard on the existing Continental 245/45 R19 tyres and we are advised to replace the two front ones with Nexen 245/45 R19s. Will this give a more comfortable ride? GP

Heavy front tyre wear on a front-wheel-drive SUV on unsuitable 245/45 R19 tyres is not unusual. Changing to a different brand of the same size tyre won’t make a major difference. The fact that the tyres have worn in the centres of the treads indicates that they are probably over-inflated and this would cause the harsh ride. According to www.wheel-size.com you could change all four tyres to 225/50 R19 rubber that would give a bit more compliance without replacing the wheels as well. Otherwise, switch to smaller (18- or 17-inches) with appropriate tyres. In all cases, you need to disclose the “modification” to your insurer.

Underneath the arches

I have an immaculate, 26,000-mile 1999 Mazda MX-5 Mk2, bought in 2003. During its 17th annual service the dealer spotted some rust at the bottoms of both rear wheel arches, behind the seats, and advised getting it sorted as in future it could be an MoT failure. Should I try to find an MX-5 specialist? Or should I let a local accident repair shop deal with it? JB

It’s a very common issue and could be structural. I would take it to an MX-5 specialist rather than a bodyshop directly, to make sure they are not only repairing it but addressing the cause of the corrosion.

Glass act

I have a 2013 Citroën C5 Tourer on which both front windows jammed open due to regulator failure. Citroën reported that the regulators were only available as complete units, with motors, even though the latter hadn’t failed. My warranty provider would not cover the whole cost (unsurprisingly), so I emailed Citroën UK Customer Services, which responded that the regulators would be available from my nearest main dealer, less the motor, at half the original price. I am very pleased to report such good service. EC

Very good news – many thanks for the feedback. 

  • Read Honest John's latest column on telegraph.co.uk every Friday from 10am

For tips and advice, visit our Advice section, or sign up to our newsletter here

To talk all things motoring with the Telegraph Cars team join the Telegraph Motoring Club Facebook group here

A-Z Car Finder