What I'd also like to know is, "Describe the other 20% of your driving that isn't on the highway."
This raises an interesting point. Because of the way the EPA sticker on our cars list "City" and "Highway" MPG estimates, people tend to lump their mileage into these two categories. But in reality, there's a spectrum that spans between "city" and "highway".
For example, I would say that 60% to 80% of my driving is truly "highway" where I can get up to 60 MPH, and then set my cruise control and drive for an extended period of time with little gas/brake intervention. The other 20% to 40% of my driving is a mix of typical suburban driving, with a stop sign or traffic light every half mile or so, and some nasty rush-hour traffic jam traffic where I'm creeping for a mile or two until I get past the accident on the shoulder of the road that's causing the delay.
It would be interesting to know (and can probably be determined by reading the EPA description of their testing procedure) how the EPA defines "city". Is my suburban driving considered "city"? Is my traffic jam driving "city"? Or is "city" something in between?
A similar question could then be asked of VWGTI's driving conditions. Is the 20% of his driving that isn't highway more like my suburban driving conditions, or is it more like my traffic jam driving conditions? Judging from the way he gave up a GTI that he liked so that he could have an auto tranny car, I'm guessing that his 20% is more like my traffic jam driving conditions; my suburban driving conditions aren't annoying enough to make a driving enthusiast give up his clutch.
I'm going to assume a couple of things, and invite others to correct me if I'm wrong:
- The EPA's definition of "city" isn't as severe as bumper-to-bumper traffic jam driving.
- VWGTI's non-highway driving is more like traffic jam driving, and is therefore more severe than what the EPA defines as "city" driving.
And if these assumptions are correct, then they explain why VWGTI can't hit the EPA's estimates. I think 20% of his driving is more severe than the EPA's city fuel economy test.