Prius fuel economy at higher speeds tested

[clett]

A german car magazine has tested lots of vehicles for high speed fuel economy:

http://www.greencarcongress.com/2006/05/fu...mptio.html#more

If you're interested, the Prius managed 20 mpg US at 110 mph!

Click here for chart of Prius vs Opel (GM) Zafira mpgs at highway speeds

[Vagabond]

Interesting. My display shows 26 mpg at around 107.

[brandon]

Those results look a little odd to me. I just got back from a 300-mile trip of almost entirely interstate driving (70 mph) and averaged almost 49 mpg. Their chart seems to indicate they were only getting 33 mpg at that speed.

[sdsteve]

<div class='quotetop'>QUOTE(brandon @ May 22 2006, 06:18 AM) [snapback]259169[/snapback]</div>

Those results look a little odd to me. I just got back from a 300-mile trip of almost entirely interstate driving (70 mph) and averaged almost 49 mpg. Their chart seems to indicate they were only getting 33 mpg at that speed.
[/b]

Too much variability in real driving. The report is as reliable as EPA, which is horribly unreliable - they just use a different measurement scheme which makes the Prius seem low.

REAL driving includes the following:
Terrain changes (uphill, downhill, flats)
Stops and starts (either local driving or traffic conditions), or just general speed changes (coasting downhill)
Environmental factors (temperature and humidity which may effect the MPG)

For example, I admittedly drive around 70 on the freeways, and sometimes faster. However, according to the gauge in my old BMW, my average speed over the past 7 years is only 42 MPH. Makes a big difference on my fuel economy. My Prius is getting around 43.5 (which I'd like to get up, but only had it for a few weeks), while the lifetime on my BMW was 23.1.

[Potential Buyer]

Just because they got worse results than people usually do, that doesn't mean this test is unreliable. The point is to compare the cars, and all of their cars were equally low-mileage. Obviously a Prius doesn't get only 30 mpg at 80 mph, but likewise a Golf TDI does not get only 36 mpg at 80 mph. They were obviously driving the cars hard, harder than just cruising at a fixed speed like it sounds like.

[donee]

<div class='quotetop'>QUOTE(Potential Buyer @ May 22 2006, 08:52 PM) [snapback]259467[/snapback]</div>

Just because they got worse results than people usually do, that doesn't mean this test is unreliable. The point is to compare the cars, and all of their cars were equally low-mileage. Obviously a Prius doesn't get only 30 mpg at 80 mph, but likewise a Golf TDI does not get only 36 mpg at 80 mph. They were obviously driving the cars hard, harder than just cruising at a fixed speed like it sounds like.
[/b]

Hi Potential Buyer,

Probably the difference is due to the closed coarse driving. In the curves the differential heats up more and there is more tire friction.

Diesel has 113% the fuel energy of Gasoline, at least in the USA on average. So, 30 mpg in a Prius is equivalent to a Diesel doing 34 mpg. Which gives the TDI only a 2 mpg advantage. Wonder what a Prius with a Turbo exhaust heat recovery system (true Miller cycle engine) would perform at?

[vtie]

This actually confirms my own personal experience: at virtually any speed on the highway, a diesel is more fuel-efficient than a Prius. This is logical because you don't really get a big advantage from the hybrid system, a diesel engine is inherently more efficient and diesel has a higher energy density.

On the other hand, for stop-and-go traffic, the Prius is definetely more efficient. This clearly shows that the regenerative braking is working very well.

Now, if only we could have a diesel hybrid with particle filter, ureum injection system for the NOx, and the HSD system...

[judibob]

Vtie --
Isn't gasoline HHV greater than diesel fuel?

[Charles Suitt]

<_< May last two "road trips" of 265 miles & 340 miles, cruising at 70-75 MPH (with bursts to 80+ to pass slower traffic), I achieved 54.5 MPG and 49.8 MPG. The lower MPG resulted from rather heavy crosswinds. Around Dallas metroplex, stop & go driving, I usually run 42-45 MPG (calculated).

Can't complain. That's twice the MPGs of our '96 Camry 4-cyl.

[windstrings]

<div class='quotetop'>QUOTE(Vagabond @ May 22 2006, 04:29 AM) [snapback]259151[/snapback]</div>

Interesting. My display shows 26 mpg at around 107.
[/b]

Hey.... not bad!