Consumer Reports tests fuel efficiency vs. speed; Honda Insight biggest loser
2010 Honda Insight - Click above for high-res image gallery
The faster you drive, the more fuel you use. Common sense, right? Absolutely, but it's still helpful to see real-life data, as you'll see by checking out the results of a recent test performed by Consumer Reports. Not all cars perform the same at various speed limits, and as you might expect, America's most fuel efficient models are also the vehicles most affected by speed.
A total of seven vehicles were tested by CR: a Acura TSX with a 2.4-liter four-cylinder; a new 2010 Honda Insight; a Lexus RX350; a Mercury Mountaineer with 4.6-liter V8; Toyota Camry and RAV4 with 2.5-liter four-bangers; and a Toyota Yaris with a 1.5-liter four.
As you're probably aware, today's hybrids are optimized for high fuel economy at city speeds and therefore lose much of their miserly ways on the highway. As it turns out, this was especially true of the new Insight hybrid, which lost over 15 miles per gallon moving the needle from 55 mph to 75 mph – the largest drop in the contest. Click here for the complete test results.
Gallery: 2010 Honda Insight
[Source: Consumer Reports]
Reader Comments (Page 1 of 2)
Boyprodigy1 6:07PM (9/10/2009)
While the insight lost the most efficiency, it was still the most efficient at 75mpg. I give this study a FAIL...
Besides that, as one of the commenters pointed out, this is one of those circumstances where gallons per mile would be more useful than miles per gallon. The 6 mpg loss of the mercury mountaineer is as bad a loss in efficiency is as bad if not worse than the 15mpg loss of the insight.
Reply
Chris M 1:22AM (9/11/2009)
You've confused the old Insight, a two passenger ultralight and ultra-streamlined car that was discontinued, with the new 2010 Insight, a 4 passenger lower-cost and much heavier car. The old Insight was the one that could sometimes hit 75 mpg, but the 2010 Insight is not as fuel efficient and rarely goes over 50 mpg.
Ghen 8:48AM (9/11/2009)
as BP1 pointed out, here's the real math:
http://spreadsheets.google.com/pub?key=tjEQaa2gtBEbRiWqqZkVgAA&output=html
I'm excited because I drive a Yaris... fast lol.
Boyprodigy1 10:37AM (9/11/2009)
Sorry, meant MPH not MPG
ABC 12:09PM (11/17/2009)
+1
Joeviocoe 6:11PM (9/10/2009)
A bit misleading... of course the best "in the city fuel economy" is going to have the "most" to lose by going up to highway speed.
But the title makes it seem like other cars tested got much better MPG on the highway as the Insight while in reality they are still way below what the Insight got (36.5 MPG). Yes since it is a hybrid that gets back lost braking energy but cannot recover the energy lost to drag, the paradigm of getting better highway MPG is reversed.
But that does not mean the hybrids are not still king of efficiency both on and off the highway.
Reply
Ray 6:27PM (9/10/2009)
What ever happened to the almighty Prius in this test? Surely it should have been in this as the most popular hybrid. They had my car in there. http://www.evalbum.com/1892
Percentages would have been convenient to! The math is to hard for me.
Reply
David Martin 7:09PM (9/10/2009)
Percentages efficiencies at 75mph vs 55mph:
Acura 76.8%
Insight 70.3%
Lexus 74.4%
Mercury 74.7%
Camry 73.9%
Rav4 74.8%
Yaris 80.0%
So the Insight looses most by going up to 75mph, or gains most by sticking to 55mph, whichever way you want to look at it.
The big shock to me is how well the Yaris does at speed, as it is not very streamlined.
Ray 7:51PM (9/10/2009)
Thanks David Martin, so in ascending order the super Yaris is first!
Yaris 80.0%
Acura 76.8%
Rav4 74.8%
Mecery 74.7%
Lexus 74.4%
Camry 73.9%
Insight 70.3%
The Yaris must just have an engine that likes to cruise at high speed. I assume these were stick shifts? Camarys don't come in a stick do they? May be they are automatics.
Ghen 8:50AM (9/11/2009)
My yaris 5 speed manual cruises at 65 at 3000 RPM. It's definitely an engine that likes speed compared to the other sub-compacts that I test drove.
Snowdog 7:26PM (9/10/2009)
One of the commentators has some spreadsheets.
http://spreadsheets.google.com/pub?key=tjEQaa2gtBEbRiWqqZkVgAA&output=html
With gallons/mile, difference in gallons/mile, ratios, everything.
Here the MPG is kind of useless if you are using it for a difference calculation, which doesn't tell you anything useful. But it is OK for the mpg ratio calculation.
The Yaris is the big winner. Smallest fuel use increase, smallest percentage drop in mpg. It must be more aerodynamic than it looks.
The Insight Aerodynamics don't seem to hold out well at high speed.
Too bad Jetta/Prius were not included, to see how their higher speed cruising abilities held up.
Reply
martin.belzile 12:09AM (9/11/2009)
This article is wong because we can't substract MPG. For exemple the difference between 5 mpg and 20 mpg is 300% and the difference between 45 and 60 mpg is 33%.
The result for none hybrids cars is exactly the opposite when we calcul it in gpm.
For the perfect car the ratio should as low as 54%. The difference is more 70% because perfect car don't exist. The prius ratio should be approximatively 65-69% because it very efficient at low speed.
Dave D 12:37PM (9/11/2009)
Good point Snowdog...I'd love to see the Jetta and the Prius in this exercise. How could they have done this and left what are probably the most talked about "high mileage cars" on the planet out of the discussion???
Oh well, I shouldn't complain as they're at least trying to get some data for us.
Michael Hippenhammer 11:44AM (9/11/2009)
Yeah, where were the Jetta and Prius? I drive mostly highway and this test fits me perfectly. Helps me make a comparison in my world.
Reply
Dave D 1:13AM (9/11/2009)
Actually, the Yaris performance on the highway is not surprising at all. The efficiency at highway speeds is determined by two things mainly:
1) Rolling resistance
2) Coefficient of Drag x Frontal Area (CdA)
The rolling resistance is at least partially determined by the weight of the car and the Yaris is 500 lbs lighter than the Insight.
The Coefficient of Drag is .29 for the Yaris vs .28 for the Insight (very close) and the Yaris is a smaller car and has a smaller frontal area (I can't find the exact numbers on the frontal areas, but the Yaris is smaller).
This means that the Yaris CdA would be lower than that of the Insight. Aerodynamic drag is the single biggest factor in efficiency at highway speeds so it would actually be expected that the Yaris would be relatively better than the Insight when comparing its highway performance to its city performance.
Of course these are percentages when comparing highway vs their city mileage, not the raw numbers in which the Insight is still getting the best absolute numbers.
Reply
David Martin 4:13AM (9/11/2009)
You'll note that the Yaris also has a small engine, just like my little VW Polo.
They must be optimised to perform well at motorway cruising speed, as otherwise highway driving would be difficult with such a small engine.
Pleasantly enough it means that I can cruise comfortably at 80 without too big a hit on fuel, although doubtless I am loosing some of the advantage I would otherwise gain in city driving.
A great deal of that should be recoverable by stop-start technology in the next generation.
b33gee 11:53AM (9/11/2009)
Where is the Jetta TDi in this comparison? The Diesel would have creamed everything else in this test. Creamed. Like Corn.
Reply
Stan Peterson 5:45PM (9/12/2009)
The Insight is a total Fraud. If any other manufacturer than Honda introduced a mild hybrid they would be laughed off the floor.
Honda is using up it hard won reputation on this joke of a hybrid. But after around of artificial initial applause, it has rapidly turned to sour critiques as it should have from the very beginning.
Reply
OpenMinded Patriot 7:40PM (9/12/2009)
Using Gallons per Mile - the Insight was the winner at each speed tested, 55, 65, and 75 mph.
Using Mile per Gallon - the Insight was the winner at each speed tested.
The Insight was the most efficient car throughout the test.
Jeremy - how can you headline "Insight Biggest Loser" ?
( and ditto re: the Prius and the Jetta )
Reply
Lucien 12:10PM (9/14/2009)
Well can I turn it around and say the Insight (=hybrids) gains most in fuel efficiency in city driving compared to highway driving:-)? And as pointed out it still has best highway FE even compared to smaller Yaris.
Ridiculous article if you ask me if they are missing this obvious fact...
Reply