Prius loses out to VW on Autoweek mileage test

I can't tell you how many articles in the past which took newbie drivers into a Prius and VW Jetta found the Prius to be out on top. This is the first article I've read of where the Jetta TDI got out on top. No excuses here. Even Consumer Reports gets higher fuel economy with the Prius than the TDI.

<div class='quotetop'>QUOTE(judibob @ Apr 22 2006, 10:52 AM) [snapback]243620[/snapback]</div>

http://mdahmus.monkeysystems.com/blog/archives/000249.html

This guy on livejournal posted the results of a real-world test in Canada involving some cars we're all familiar with. As with CR's results, in a real-world test, the small diesel car didn't even come close to the mileage of the bigger (midsize) Prius.

http://cychan.livejournal.com/27645.html

http://mdahmus.monkeysystems.com/blog/archives/000247.html

Car City Hwy 0-60 time
Jetta TDI 24 mpg 46 mpg 12.2 seconds
Civic Hybrid 26 mpg 47 mpg 11.7 seconds
Prius 35 mpg 50 mpg 11.3 seconds

(I never thought I'd be using Consumer Reports figures to make a point!!!!)

 

it is possible to get better milage with the TDI, just do the test on all highway at 60+mph.
see here

 

As it is with the Prius. Get one of PC's drivers and you will get higher fuel economy with the Prius. And I would suggest higher temps.

<div class='quotetop'>QUOTE(kDB @ Apr 22 2006, 11:33 AM) [snapback]243636[/snapback]</div>

More articles for your reading pleasure:

http://www.caranddriver.com/comparisons/84...pics-page3.html

Mileage on the Highway
All four cars got more than 40 mpg, and the Prius hit 50. Amazingly, the One-Calorie Toyota Echo squeaked above its EPA highway number (39) to 41 mpg. The diesel, at 42 mpg, fell 2 mpg behind its EPA rating.

Mileage in Town
The Prius again scored at the top with 52 mpg. Dr. Diesel, in last place at 33, was a bit of a surprise. We expected more. Diesels are at their best, relatively speaking, under light loads; they inject very little fuel and they have no throttling losses. Again, the One-Calorie Echo did superbly at 42 mpg.

 

<div class='quotetop'>QUOTE(judibob @ Apr 22 2006, 08:53 AM) [snapback]243640[/snapback]</div>

Tell a German car there's beer at the end of the trip and it will do anything you ask of it.
(Did the writers say how much they'd consumed when calculating mileage?)

 

<div class='quotetop'>QUOTE(Mirza @ Apr 22 2006, 11:30 PM) [snapback]243629[/snapback]</div>

It depends on the method of testing.

I have read extensively on the internet, articles about Prius/& other hybrid fuel economy and some report that on long highway journeys, especially at high speeds, hybrids generally do not provide as big a FE advantage as in stop start city and surburban driving. This is logical as, at constant highway speeds, storage (in battery) does not play a significant role.

In a recent comparison between the Lexus RX400H and a diesel Mercedes SUV they also reported, in a coast to coast comparison, that the Mercedes diesels consumed less fuel than the hybrid.

http://www.carpages.co.uk/mercedes_benz/me...ss-25-08-05.asp

Both reports were based on long highway runs. But if they tested the cars in the city the results would be different.

 

<div class='quotetop'>QUOTE(judibob @ Apr 22 2006, 11:53 AM) [snapback]243640[/snapback]</div>

It's funny, diesels seem to better in real life than in our UK official tests too. A Prius was recently driven 840 miles from top to bottom of our country (you can read all about it here). They were trying their best to hypermile, and managed 57 mpg (US) but at a relatively slow average speed of 38 mph over the whole trip.

On the other hand, a diesel car of similar size, weight and Cd to the Prius (an Astra ECO4) was driven on the same 840 mile route, and managed 75 mpg (US) at a considerably higher average speed of 53 mph.

Otherwise the Prius and ECO4 have pretty much the same EU combined cycle official mpgs (about 54 mpg US).

 

One Prius driver drove around the same speed as the test you mentioned and had gotten 85.7 mpg.

http://priuschat.com/index.php?showtopic=4400&hl=85\.7

<div class='quotetop'>QUOTE(clett @ Apr 22 2006, 12:16 PM) [snapback]243649[/snapback]</div>

 

EPA calculations for gas mileage are 30 years old and don't accurately reflect real world changes in cars since the 70's, nor changes in driving habits. The Union of Concerned Scientists had an article in the spring06 Catalyst magazine about this. They observe that we are driving at higher speeds. Fuel economy drops about 10% between 55 and 65mph, 17% between 55 and 70mph. Cars on average now accelerate faster. That extra power burns more fuel. More congestion on hwys: traffic jams have quadrupled between 1982 and 2001. EPA data shows that almost two thirds of driving is done in urban areas, idling reduces gas mileage dramatically. We're driving shorter trips, average is now less than 5 miles, yet EPA calcs are based on 11 mile trips. Most cars aren't operating at peak efficiency with these shorter trips. Heavier engine loads: 99% of new cars now have A/C, many run the A/C while defrosting, yet fuel economy tests are done with the A/C off. And there is no allowance for new technologies like engine deactivation, shutting off cylinders, hybrids, etc.

The EPA has proposed modifying rules and introducing new tests such as: US06 which simultates high-speed driving (up to 80 mph), SC03 which simulates hot weather (95F) driving with A/C on and Cold FTP which simulates driving in cold (20F) weather driving.

 

If you are investigating a new drug, and 20 studies show one result, with one showing the opposite, what do you do first?

1) Demand that the 20 studies explain themselves?

2) Investigate the methodology of the outlier?

Without knowing the exact test or methodolgy, I would suspect the 'one tank' factor first. Unless they do something like fill to the top of the filler neck each time, the Prius tank variations can be very large, as we all know.

 

<div class='quotetop'>QUOTE(judibob @ Apr 22 2006, 10:52 AM) [snapback]243620[/snapback]</div>

Yep, car magazine drivers do not lift throttle. The Prius senses where you have your foot on the peddle. If you pull back alllot and bring it back up, the computer will reconfigure for efficiency. If you accellerate and then pull back just a little, like in a standard car, the Prius is ready for action, and keeps the car configured for agressive driving. It wont warp stealth, and it wont stealth at all, and it may even keep recharging the battery up to the green bars. Which then disables regeneration. Poor mileage inevitable. It took me a few weeks to realize I had to lift the throttle ALL the way back.

Another spin on your EPA test comment, as I am getting right at the EPA rating for mixed driving here with my Prius. MY REAL WORLD must match the EPA's, then, eh?. A weekday, low-traffic highway romp over to Holland, MI is NOT MY REAL WORLD. Slow and Go in surburban highway traffic is. From my experience your conjecture that other cars are designed for real world fuel economy is malarky. It seems they are designed for spring and fall highway driving with the results you mention. Which is the real world for college students not living at home and touring rock bands.

Want to make a Prius do poor on a gas refill computed mileage in the midwest spring? Fill the tank at subfreezeing weather in the morning, run all day for 450 miles , and then refill at 50 degrees in the sunny warm afternoon. Result, Prius will take 1 gallon more gas in the evening than the morning. Computation is now screwed up. Did Autoweek measure gas consumed, or just retank volume? Try deducting a gallon from the gas Autoweek refilled the Prius with and see what the result is then.

 

You certainly bring up a good piont about the gas tank bladder. It's been a topic of discussion when past articles like this came up.

<div class='quotetop'>QUOTE(donee @ Apr 22 2006, 12:48 PM) [snapback]243663[/snapback]</div>

 

<div class='quotetop'>QUOTE(Gerald @ Apr 22 2006, 01:11 PM) [snapback]243648[/snapback]</div>

That seems to be a common idea that many articles/people use to say hybrids are "bad" on the highway.

The battery may not play that large of a role, but you have a smaller ICE than most other vehicles, so it it still relatively efficient at highway speeds. Driving at highway speed (65-70) we range from 50-55 mpg and on the interstate (70-75) we get 45-50 mpg. The only other cars that can reach that are either hybrid cars or diesel. The city improvement can be higher, but there is no doubt in my mind (and in the numbers) that there is still a significant benefit in a hybrid on the highway (in the neighborhood of 30% improvement). Of course, compared to 60% to 100% improvement over similar sized cars, 30% doesn't seem to be that good, but who wouldn't take 30% better mileage if given the opportunity? It's only when people compare that to the city improvement that all of the sudden hybrids are "inefficient" on the highway.

 

Diesels should do relatively better than the EPA compared to normal gas cars. That is because the EPA fakes the results to compensate for some losses from start up, idling, stop and go etc. And diesels lose less than the gas cars on this stuff. The measure stuff and then correct by some fixed percentage. This is why some Prius drivers too can beat the EPA numbers.

But the Prius should still win easily, so I agree, with the other posters. If they measured the fuel used by just filling the tank then I can prove my Prius gets about 80 mpg or more! All fake!
And not just from temperatures either. The fill ups vary due to the bladder getting a wrinkle etc at any temperature. I get no consistency from tank to tank, so I ony use the pumped fuel numbers when measured over 10 consecutive tanks at least.

 

<div class='quotetop'>QUOTE(clett @ Apr 22 2006, 11:16 AM) [snapback]243649[/snapback]</div>

Haven't got time to read the "diary", yet, but something seems suspicious here. Given the cars equal footprint on the road, the astra would expend about 2 times the energy to complete the trip (53 mph/38 mph squared over the same distance, assuming constant speed, which its not). I'll grant that diesels are more efficient ICE's, but 150% (twice the energy, 50% less fuel)?

 

Hi Judibob,

Sorry to have posted something you found nasty. I thought I would write a strident response in the same style as your strident original post, but with the antagonist position. On the real world thing, yea nobody likes having generalities applied that do not match their situation - Autoweek's or the EPA's . Also have seen allot of media spin lately. And thought I would spin back.

When I was a grad student, my main use for the car was to drive to the parents house on the odd weekend, or holiday. I road my bicycle around campus, and took the bus into town. Car sat. My real world then matched this test. It does not now. And of course touring rock bands typically drive during the mid day, setup and play in the evening, and sleep the rest of the time. This also matches the Autoweek test situation.

The Autoweek test occured in 46 F ambient conditions, what one finds in the mid spring or mid fall here and where the test took place. This weather is typically subfreezing in the morning, and low 50's in the afternoon. The length of a drive from Detroit to Holland, MI, with lunch at noon time could very well encompas these temperatures, and be at 46 F nominal. On the other hand there are many Prius owners who have made their detailed fuel consumption records available on the Internet. Comparing those against detailed TDI owner records might be more enlightening than this Autoweek test.

People using a car to commute typically get up in the early morning, drive to work with allot of other people on the road at the same time, work, then drive home with a bunch of other people on the road at that time. Car magazine tests have yet to test with a commuter cycle that I know of and are thus no closer to commuter real world than the EPA testing, consequently. Its this situation where the Prius shines, not constant speed on the highway. Want to design a test to bash the Prius, do it like Autoweek did. Want to design a test to bash the TDI, keep metropolitan commuting fuel economy records.

 

Ok, venting time...

I am sick and tired of articles, or people, for that matter, that put down the Prius. Sure, some of them dont like the looks of the car, and I can live with that. There are those that have called it anything from a 'geek mobile' (and I do admit to being a confirmed geek) to a car that is simply way too expensive. This, from my own family. And one of them owns and Audi...he has to put Supreme gas into that thing. I have learned to shut up about my gas mileage, as it has made some friends rather upset...and this at church, even. I have learned that the Prius is a different car, and it is not to be driven like some hot-rod or sports car. The challenge of the Prius is in getting good mileage while not polluting the environment rather than burning doughnuts in the street. Here, gas is over $3 a gallon and people are still doing 75+ mph on the freeway. During the first oil crisis under Jimmy Carter, everybody slowed down and gas was rationed. I do not understand why people think that they can get away with simply driving-as-usual.

Sorry for the rant. It is not that I 'feel smug' because I own a Prius. Rather, I wonder why others dont try to save gas, too, if only in changing their driving habits. But, I know all too well that the only thing I can change is me, so I can live with it. I do get frustrated sometimes, though.