3 ms·

It totally can be that easy, though. Imagine the software in the car has the following pseudo-code… if (emissions_test_running()) { run_efficiently(

• alkonaut 9y ago
  No, you have that backward a bit: the NOx emissions are high when the car runs efficiently (high compression/temperature) So you can make the engine run at high temp, do 5L/100km and output 200hp, but with lots of NOx produced Or you can run it cooler, with less NOx produced, but then it does 6L/100km and ouputs 175hp (say) So basically the bad code was if (under test) run_cool_inefficient_lowNOx else run_hot_efficient_highNOx The reason why many diesel manufacturers cheated is because the numbers for diesels are only good if you run hot. All that low consumption, high power etc comes from its ability to run hot, but then it spews NOx. This was made worse by EU regulations that focused 100% on CO2 - which is proportional to consumption only. In order to sell cars in the EU they needed models that stayed under 120g/km CO2 (say 5L/100km) and of course they couldn't be lower power than the competition, and to stay under price limits for company purchases they needed models that stayed under the price limit where they could fit AdBlue systems