Many in the Volkswagen diesel community are fanatical about their fuel economy and are understandably angry that a fix for the current emissions scandal may see them lose fuel economy in order to lower NOx output. The aftermarket community has provided modifications for the DPF and Adblue systems in the past, meaning there’s good chance they’ll provide parts and tuning to revert any changes Volkswagen may implement on the affected models.
There are a number of paths which Volkswagen may take that range from an ECM patch to new SCR hardware that could be installed.
The non-SCR models may get a software patch that would alter the injection timing and increase the regen cycle. This would cause the NOx emissions to go down but would take fuel economy and power along with it. It could also cause carbon build-up on the pistons and catalyst which could lead to increased maintenance costs for the owners.
The other path for the non-SCR cars is implementation of an SCR system, but that may not be cost effective due to the parts cost and labor required. I speculate that the SCR cars could receive an ECM patch that would increase regen cycles along with increasing the amount of Adblue that would be dosed. This would work out better than any fix for the non-SCR cars but would still result in higher Adblue costs.
Owners may look to the aftermarket to defeat these fixes so that they can keep their power and fuel economy.
The aftermarket community has released modifications for the DPF and Adblue SCR systems long before there was any talk of reduced power and economy coming from a potential fix for the emissions scandal. They looked to gain more power and better fuel economy by modifying or deleting the DPF system. Aftermarket tuners such as Rawtek and Malone Tuning produce kits for DPF models which replaces the DPF and EGR systems with stainless steel exhaust piping and tunes the ECM for better fuel economy and performance. They mark these systems as off-road only as they violate federal emissions laws. Rawtek also produces a kit for the Passat that deletes the Adblue SCR system along with the DPF and EGR and also advertises gains in power and fuel economy.
The tuners responded to the VW stop-gap recall which was released a few months ago, Volkswagen’s attempt to curtail this emissions scandal. The tuners let the owners know that they can revert the recall programming and reflash their previous tune for a minimal cost. The current versions of the ECM hardware and firmware may become an avenue for re-flashing if there is demand from owners after the recall fix as it would allow their vehicles to be reverted back to the programming they had when they purchased the vehicle.
In the end, unless Volkswagen implements some sort of encryption or lock on the fix, owners looking for power or economy will look to the aftermarket and revert back any emissions improvements that are made.