Real World MPG & emissions data

[SteveMak]

re: Gap between official figures and real world numbers

Manufacturers are not required to meet real world fuel economy or emission metrics. They only have to attain specific numbers when operating under very specific "in lab only" conditions -- which do not resemble the real world -- and accomplish this without using the legal definition of a "cheat device."

Every vehicle sold either meets these legal "in lab only" requirements, or is falsifying certification documents.

VW met these "in lab only" requirements, but they used a cheat device. That's why they're in hot water. Virtually all vehicles sold do not meet these "in lab only" limits when they operate under real world conditions. That's not against the law, and that's why nobody is complaining. This is, however, the reason why you are seeing the widening gap between "official" numbers (those in the lab) and real world numbers (those the vehicles actually produce when operated in the real world).

When the vehicle test cycle closely resembles real world driving conditions, then we'll see the gap narrow dramatically or disappear altogether. The more closely the certification conditions resemble the real world, the narrower the gap becomes.

Meanwhile, on American forums, many members argue it's impossible to certify emissions to real world condition, so that's why it makes sense to keep the existing in-lab-only system, which has been proven to be nearly useless. The argument is that it's better than nothing.

I'm in favor of emissions and fuel economy tests that are as close to real world conditions as possible. Perhaps the law will have to define "the average driver" and "the average driving conditions". Perhaps they'll have to define a range (speed, altitude, acceleration vigorousness). I believe these humans are smart enough to figure it out.

By the way, you readers are aware that the current, in-lab-only emissions testing procedure was defined by the auto industry itself, don't you? It wasn't knowledgeable, unbiased, environmentally conscious legislators who thought it up.