Quote:
Originally Posted by sgtlethargic
How is the VW 1L prototype getting 170 mpg when 100 mpg seems like a stretch?
|
I'll second Frank's answer: optimization. It's a $400,000 economy car.
I'll add that part of the answer, however, lies in the website you referenced. Different test routines produce dramatically different mileage figures. The Riley is really a 70 mpg car (running through the EPA highway cycle) advertised as 128. The VW would not get 170 mph in an EPA test cycle. The X Prize results for the VLC are close to what the VLC would get in an EPA combined cycle (because the X Prize test was designed to be that way). They got something like 107 mpg, I think. The VW engine is probably more efficient as installed -- i.e. relative to the load. Total aero drag is lower, and if I recall, weight may be lower also. I would not be shocked at 135 - 150 mph EPA combined for the VW.
I may have mentioned this, but the Aptera with a 660cc kai engine (fuel injected gas) got 50 -55 mpg, almost all the time, according to Steve Fambro. Granted the Aptera is big, but it was very well-streamlined, and the small engine was at least pretty well-loaded. When you add a few sub-optimal choices here and a few more there, the overall efficiency can plummet.
In a plug in hybrid, like mine, there are lots of energy conversions. For the sake of simplicity, we'll say there are five processes. These can each be highly efficient: 95% .9^5 is 77%. They could each be OK: 80%: .8^5 is = 32% Big difference.