Quote:
Originally Posted by Isaac Zachary
That may be true, but also to what degree? The Freevalve engine is supposed to run nearly all the time in an atkinson cycle, but at WOT bascially goes into an Otto cycle. However, the whole time it has the same compression ratio. I suppose the same can be done with variable valve timing on any engine. But again, the CR doesn't change. On a Prius the CR is extremely high, but is compensated by the engine always running in an Atkinson cycle.
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Just about all the time, really. It's a non-hybrid with a 14.0:1 compression ratio, so it's bleeding off a lot of that cylinder pressure through the Atkinson cycle, while keeping the expansion ratio, even with the throttle wide-open. Tuning it for power is basically an experiment in seeing how
little you can bleed off at WOT.
By comparison, the 4th gen Prius only has a 13:1 CR, and the Freevalve engine is only 9.5:1 - though that one has around 30psi of boost.
EDIT: It's a bit beside the point however, when both Honda and Toyota have engines with lower compression and higher thermal efficiency.
Quote:
Originally Posted by Isaac Zachary
The 1979 Super Beetle had a highway fuel mileage of 30mpg. The 2003 Digifant Beetle (Mexico) was rated at 32.5mpg (although I think that's combined, I remember highway being like 38mpg). Some have claimed to get up to 40mpg through mods and hypermiling. I got 30mpg on the highway in my 1972 Super Beetle. Other body designs using the same engine got better fuel mileage (e.g. Karmann Ghia).
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Surprisingly good. I wonder if part of that is not having a bunch of parasitic accessories like water pumps and power steering.
Fuelly seems to suggest real world mixed driving economy is a bit lower:
https://www.fuelly.com/car/volkswagen/super_beetle
Reading Quora, most owners there suggested they were seeing 25-28 highway.
The median is ~23mpg, right around what a new F150 gets in mixed driving.
That said, I 100% understand the appeal of having an engine with no electronics, that you can rebuild for $200 - even if it needs that rebuild every 75-100k or so. So long as rust doesn't take it, that's a vehicle that doesn't have an expiration date.