Mind you not by choice.
"A 4 cylinder diesel, with a manual transmission, totally durable, ideally painted green, working on a farm." Summary of our perspective at the time.
We are aware of call it a "catalytic converter" for diesel engines, the ones for trucks are positively impressive in size.
Why are we not fans of diesel engines in cars? Simple the lack of top end power, the glow plugs, and now the converter with urea. An hybrid from our perspective makes better sense.
In a truck we are huge fans of diesel engines, and will always have a special place for the 2 cycle Detroit Diesel, with the blower, unit injectors, fuel injector racks, and fond memories of discussions on how to adjust the racks on a V8 Detroit.
The heavy duty pick ups with diesels are totally cool.
Here is VW with an interesting niche in the market for folks that love diesel engines in cars, like we love diesel engines in trucks. Diesel engine, manual transmission, the economy and durability....fill it and forget it, its got a clutch pedal, will presumably last till the next generation.
Emission standards are strict in North America, these diesel VW's are in a sensative price bracket, the cost of a catalytic converter with urea is prohibitive for that price segment.
How do you find a cost effective solution to meet emission standards, and pass emission tests?
If you live in a jurisdiction where emission tests are mandatory. The old school put the vehicle on a dyno, run it for a while, and sniff the exhaust, has given way to simply plugging into the OBD and revving up the engine to a specified RPM.
Here is the deal...
"We can pass emission but at those settings the engine loses a ton of power, and the vehicle is dead on the road"...."But what about on a dyno, or plugged in to check the emission"...."Brilliant..and an effective cost saving".
As they say the rest is history...
You would do such a thing for 1 vehicle, or you do it for several vehicles, for several years its the same decision on a different order of magnitude.
"We used the European ECU codes (cost saving), while adding a few lines of code to ensure that the emissions were correct, but omitted to remove line 308 of code"....."Unfortunately it fell through the cracks for all those years, and all those cars. We are deeply sorry"
Its an ongoing developing story...with dire consequences for VW.