[baobabaobab]

At least in my corner of the industry (commercial) , we've been asking for better test cycles because we don't want to wind up in a situation where we are chasing fuel economy on the test cycle at the expense of fuel economy in the real world. The regulators want to keep the same test cycles so they can measure how emissions and fuel economy are changing over time.

Internally, we have much better test cycles correlated to real world routes that we use to validate fuel economy simulations.

[bsdetector]

I don't understand why regulators don't just do additional, more representative tests so they can track long-term trends and also have a better test? How much time/resources do the tests actually take?

[myhf]

A more representative test (like running a car on a treadmill) requires a dedicated testing facility that nobody wants to pay for or wait in line to use.