Dear Doctor,

There have been many reports in the media, and on some Volkswagen Audi web forums, that the emissions software updates on Volkswagen Group TDI engines affects the engine torque by reducing the rate of fuel injection at the lower end of the rpm range, thus reducing acceleration. I do not wish to have the update carried out on my car, which is a 2012 Volkswagen Golf 2.0 TDI Mk 6 model. Please can you tell me if the update is mandatory, and if I am required to have it done, or can I simply not get it done, if I so choose?

Thanks for your advice,

Richard Gillingham

Hello Richard, and thanks for your letter, that will interest many readers that own a Volkswagen car, I am sure.

Below is a statement made previously that I have no reason to believe has been countermanded. I have not myself come across these suggestions that performance is significantly compromised after the software modification, but I will look into this further and hopefully come back with more information. I’m suspicious of the suggestions of any restriction of lower engine range fuel injection rates, and thus power reduction, because it is generally at the top end of the engine speed range that most of the NO_x is generated, and most of the power also, if you think about it. If I had to put my money on it, I would bet that the “defeat device” was set to reduce or bypass the EGR (exhaust gas recirculation) system during EC regulatory testing, and that this is what is being modified now.

Of course the whole thing is rather complex, and when Volkswagen fix the “defeat device” by modifying the software, there is no official way, or testing capacity, for the regulatory authorities to confirm it’s been done, and no way of showing exactly by how much it has reduced NO_x emissions. Volkswagen don’t seem to have been required to show anything specific on this – or at least the effect (and the nature) of the changes has not been publicised or declared. I can’t say I blame you in your attitude though Richard, and I might well do the same in your position. But I’ll see what more I can find out!

“British motorists who own cars affected by the Volkswagen emissions scandal won’t have to get their vehicles fixed when the German auto giant issues a mass recall. The Department for Transport said that drivers with cars fitted with Volkswagen’s pollution-cheating software were under no obligation to send the vehicles back to Volkswagen dealerships to get them modified. “If a driver didn’t return the vehicle, that would not be illegal,” a DfT spokesman said, although he added that failure to do so could affect any warranty on the car, as well as its resale value. Motorists would not be fined or penalised in any way if their cars weren’t fixed, “but it is in their interest to do it”, the spokesman added.”

Regards,

Doc Diesel

Then after further enquiries, I replied:

Richard, I have just had a telephone call from my A5 2.0 TDI Sportback (2012) owning relative. He has driven 2,000 miles or so since his car was modified with the recall, and he says that he can feel no difference in the engine response whatsoever, and he is still averaging 53.2mpg (using Fast Exocet fuel additive), over mixed driving, including a long, fast (but legal) drive down to Kent and back from West Norfolk. I was very pleased to hear this, as it puts my mind at rest that there is no funny business going on with the recall. Maybe you should reconsider not having the update performed now?

Best regards,

Doc Diesel

(I should add to this that I have no direct information regarding any effects of the different software updates on the 1.6 TDI and 1.2 TDI engines. Doc)

To which Richard replied:

Thank you very much for this information, it’s really good to hear from a car owner whose car has just been updated, rather than just miscellaneous rumours. Thank you for easing my fears, and I will most probably now go ahead and have my car updated. I had previously asked the question regarding my freedom of action on the upgrade at my Volkswagen dealer, who were told by Volkswagen UK that the update was not mandatory, but could be done free of charge at any time in the future, until any possible change of policy.

Thank you very much for your attention.

Richard