3 ms·
I don't understand this "defeat device". What's the incentive for VW to do this? If the car can emit in the target range during a test, why not do it all time?
by ohitsdom 11y ago
I don't understand this "defeat device". What's the incentive for VW to do this? If the car can emit in the target range during a test, why not do it all time?
- feld 11y agoProbably lowers efficiency
- masklinn 11y agoPerformances. The engine's efficiency is much lower under restricted emissions conditions. Quoting from https://np.reddit.com/r/engineering/comments/3lhhjk/have_you_ever_been_asked_by_your_boss_to_violate/cv8ypjk https://np.reddit.com/r/engineering/comments/3lhhjk/have_you... > They were caught cheating on NOx emissions primarily although all emissions are in a way connected. > NOx is created when temperatures and pressures are very high during combustion. Sadly NOx emission is generally higher when your combustion is nice and hot and rapid, which gives higher efficiency (closer to the ideal thermodynamic cycle). > […] [A lying] car will produce a lot more NOx in normal driving, and have better fuel economy. > […] If VW correct this via recall the car will be required to run on the "clean" calibration all the time. This will mean poorer fuel economy, I would be speculating to say by how much but VW wouldnt have bothered cheating if it wasnt a significant gain. It may even have implications on durability if certain parameters (like exhaust gas temps, turbocharger RPMs or oil life) are affected as they often are.