Any vehicles stand out as being exceptionally efficient at higher speeds?
 

Just a random thought today. I wonder which vehicles can get the best fuel economy numbers at steady state higher speeds, like 70-100mph? I remember reading about aerocivic's car getting ridiculously great mpg figures at high speeds, but what about the avg commuter cars?

What about VW TDIs? I would suspect they would perform well. My old 1993 burner certainly would not, it revs at 2800rpm at 60mph and only gets about 32mpg at that steady state speed...

I imagine you'd be looking for cars which have so much power that they operate at such low loads that a higher speed could be more efficient...the difference in power it takes to go 60 vs 80 is huge.

Maybe say, a 7L lambo? I could see that being possible.

VW Lupo 3L with 1.2 TDI engine:

https://www.facebook.com/photo.php?f...type=1&theater

Older VAG cars with 1.9 TDI (AHU and ALH are the best ones IMO) engines are also pretty efficient and with small mods you can get 60+ MPG @ 62 MPH speed.

My car is a normally aspirated 1.9 VAG diesel and, according to my Ultraguage, I am seeing about 70-79 mpg (imp) at a constant 60mph, and about 65-70mpg (imp) at 70 mph. (The stats shown in my signature reflect the fact that my car is mostly driven by learner drivers, and not me)

Looking at the stats on this site, I am amazed how well these cars stack up against the so much more complex hybrids. The top scoring diesel also appears to have very few aero-mods. So, looks like vehicle choice, plus hyper-miling techniques are what really make the difference!

I've just realised - I don't recall seeing any mention of BMW diesels here. My guess is they they would do well generally, but especially at the higher sort of speeds you mention..?

I drove one for a few weeks, some time ago. It was easily as economical as the VAG cars at normal speeds - but I do recall, from a short blast down an unlimited autobahn in a 3 series SE Touring wagon, that at 140 mph, you could almost see the needle of the fuel gauge moving towards 'E!'! (at the odd moment when I dared take my eyes off the road ahead!)

Quoting http://en.wikipedia.org/wiki/Drag_(physics)
"[...] the power needed to push an object through a fluid increases as the cube of the velocity."

In short, if you're looking for a vehicle that gets better gas mileage at 70 than at 60, you are not likely to find it.

on my other forum people tend to say that the oldsmobile intrigues get around 30mpg at highway speeds which the normal highway is 26mpg

My bad...

What I meant was, which vehicle would be better for a high speed highway trip.

If you took something like a Honda Insight II up to 100MPH and set the cruise, I imagine it's MPG would be down lower than the 40s would it not?

Now compare that to something like an Audi A3 TDI, or one of the VW TDIs at 100MPH. I would think that the diesel engine would attain a better MPG figure at these excessively high loads due to the nature of the diesels BSFC characteristics?

The reason I'm curious is because I'm moving soon to a remote community where the nearest destination is about 5 hours away by a very busy highway. It's a community of 80,000 out in the middle of nowhere where there is nothing to do on Friday at 5pm other than get on the highway and get the heck out of there for the weekend. It has been said that if you drive at less than 75MPH you would be endangering your life. I'm thinking that my slow and steady P&G routine would be out of the question, not to mention my girlfriend would pull her hair out, doing that for 5 hours...

I bet things like grill block, smoothed wheels, and under tray would make big gains in that scenario.

Disclaimer: I'm not saying that I would travel at these excessive speeds, but I would like to use them as a gauge for the purposes of this thought experiment.

Excellent graph Vekke, wow nearly 40MPGUS at 160km/h is impressive!

Forgive my ignorance, but what do you mean by VAG cars?

VAG is Volkswagon Automotive Group. In Europe that includes VW, Audi, SEAT and Skoda generally (though you can argue Porsche, and so are Bugatti). Lots of chassis sharing, lots of engine sharing between brands.

I'd say an Audi A2 is a pretty good small and aerodynamic cruiser, especially the 3L models which wouldn't be too hard to adapt to. Larger vehicles from VAG would do well with the 1.9 TDi unit.

On a very long run, I think in the past I've got around 60mpg (imp) traveling at 75-80mph.

I'm hoping to do better than that in May when we have a road trip across France, Belgium and Holland

Maybe 70mpg (imp) although with hypermiling it should be possible to get towards 80 mpg (imp) but not sure I could P&G that sort of distance without my left leg dropping off...