They're not going to retrofit an SCR system on to cars proven to meet emissions standards when the software is running in compliance mode. They're going to refl

They're not going to retrofit an SCR system on to cars proven to meet emissions standards when the software is running in compliance mode. They're going to reflash the ECU with software that doesn't cheat. The result for the consumer: a minor drop in fuel economy and more frequent cycling of the Diesel Particulate Filter (DPF) will have a little more noticeable impact on performance than when in cheat mode. The DPF is like a muffler with a trap to catch the soot and ash from the exhaust. That black stuff you see coming out of a truck but never from a TDI even when in cheat mode. When the DPF is cycling, the engine passes unburned fuel from intake to exhaust on every fourth stroke. The unspent fuel lands on the trap, and when the hot exhaust from the next stroke ignites that fuel, the soot and ash are reduced, which in turn reduces NOx emissions. If they are smart with the software, they'll try to run the DPF when the car is cruising not accelerating, and the impact on performance will be hardly noticeable at all. Cycling the DPF more often will likely result in a longer lifespan for that unit. Currently they need to be cleaned when they become fouled. Cycling the DPF more frequently, thus burning the soot out of the trap more regularly will likely reduce fouling.