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Another urban legend is spawned

Prius 'proven' to get worse gas mileage than BMW 520d

Posted by biodiversivist (Guest Contributor) at 1:46 PM on 27 Mar 2008

Read more about: Prius | cars | fuel efficiency | energy | green living

This story in the U.K.'s Times Online is racing around the interwebs. Google "BMW 520d" and note how many pages deep it goes. Two goofballs journalists took a road trip, one in a Prius and the other in a BMW 520d. The BMW purportedly got about 4 percent better gas mileage than the "gas guzzling" Prius, which amazingly only managed a dismal 40 mpg. Coincidentally, that is exactly what our Prius got on a road trip last summer, which was not only jammed with people and camping gear but also had a giant cargo carrier strapped to the roof! Odd how the Prius always manages to lose these contests ... unless they're performed by independent third parties like Consumer Reports (Prius: 44 mpg, TDI Jetta: 34).

The Prius has set the bar and competitors are finally going after it. This is how homo sapiens are. This is what motivates them to build skyscrapers and airliners. For the first time in human history, they are finally competing over green issues, which is all good. The following story carefully orchestrated farce is, in reality, a tribute to the Prius engineering that kicked this whole show off. Somebody has a serious case of mileage envy.

The video starts with Nicholas telling us, "We are going to see if we can get there on one tank of fuel each ... "

Okay, we have just established that these two are not rocket scientists -- the Prius tank holds 11.9 gallons compared to the Beemer's 18.5.

Next stop, Nicholas gives us a look at the BMW mileage computer. It shows 46.1 mpg. Jason tells us his computer is showing 45.3 mpg. I wonder what the readings would have been if Nicholas had been driving the Prius? Hint: you can expect to take a 2 percent mileage hit for every extra 100 pounds you carry.

Now, we have already established that these two are not rocket scientists, so when Nicholas tells us that, unlike the Prius, the BMW gets its high mileage from lots of "less radical things," you might want to take his revelation with a grain of salt. His examples are as follows:

  1. A small four-cylinder engine (like the Prius).
  2. Low aerodynamic drag (like the Prius).
  3. Low rolling resistance (like the Prius).
  4. A fuel consumption computer on the dash (like the Prius).
  5. Regenerative braking for the battery (like the Prius).

Although not mentioned, I suspect the engine may also turn off at stops and may also have electric assisted steering (like the Prius).

Next, Nicholas tells us his BMW is still getting 46.1 mpg and that he would be very surprised if Jason is keeping up with him. Surprise! No further mention was made of Jason's mileage.

Then we have Jason fretting that his tank of gas isn't going to get him to his destination. Poor Jason -- considering that his gas tank holds about six and a half gallons less than the Beemer's does, you would think he might have figured that out beforehand. Oh well. A rocket scientist would also have just stopped at a gas station and filled up rather than run the car out of gas.

Next up, we have Nicholas peering in the window at Jason, who sadly (in more than one way) has just run out of gas:

Nicholas asks, "Jason? Have you run out of fuel?"

"Uh, yeah," says a deeply chagrined Jason.

And, finally, it is time to find out who has won. What a surprise that was. A video of the average mileage displayed on each car's onboard computer as they rolled to a stop would have made a dramatic end. But remember, these guys are not rocket scientists, which may explain why no such video evidence is forthcoming. Call me a skeptic, but our Prius consistently averages over 50 mpg on the highway.

This reminds me of an earlier comparison where a Prius lost to a diesel. The Prius computer showed 51.7 mpg highway as one might expect, but the "journalists," assuming it must have been wrong, ignored it and somehow managed to calculate 38 mpg, thus launching yet another long-lived internet urban legend (along with the "Hummer is greener" and the "battery pollution" rumors).

From the article:

The official fuel consumption figure for the Prius -- supplied by Toyota itself -- is 54.7 mpg in mixed motoring. That's a claim not supported by many of the letter writers to The Sunday Times who say they get nearer to 41 mpg.

Suspecting that everything said in this article may turn out to be wrong, I checked the official Toyota website, which gives 48/45/46 mpg for city/highway/combined. The EPA gives 48/45 for city/highway and Consumer Reports gives the Prius an average 44 mpg. And exactly how many is "many"? Is it more than one?

But here is what I find amusing: the BMW only got 41.9 mpg in the test run, when the official fuel consumption figure for the BMW -- supplied by BMW itself -- is 47.9 mpg!

And finally we have these contradictory statements from Jason:

The next day it became clear my Prius did not like motorways, at least not at 75 mph into a headwind ... I'd lost to a Beemer and I was disappointed; I had never driven so slowly or carefully for so long in my life ...

The Prius is a hatchback, not a sports car. Those speeds are not in its mileage design envelope. The aerodynamic penalty associated with an abrupt aft shape is tough to compensate for at higher speeds. Driving 75 mph is a dumb thing to do for numerous reasons.

The Prius was just the beginning. Better cars will show up. This need of diesel enthusiasts to bash the Prius is baffling. In Europe, there is a 35 percent price difference between the low-end Prius and this low-end BMW. That's a steep price to pay for that purported 4 percent improvement in gas mileage.

A cheap cheat at best.

Most people drive the most miles in mixed urban/suburban driving averageing speeds in the mid-30's for stop and go commuting. A diesel in those conditions just sits and burns fuel while the Prius reverts to it's battery for power.

I suppose it doesn't matter that with off the shelf mods the Prius can easily get over 100 mpg. I wonder if that would ever be possible in that BMW?

Of course they probably didn't take into account the higher carbon content and fuel value of diesel fuel or the fact that it takes more oil to make a gallon of diesel than a gallon of gasoline. Oh, look, the Prius official CO2 rating is 104gm/km vs. the BMW's 136 gm/km.

Also that 75 MPH into a headwind speed could have been up to 105 MPH windspeed that would just eat the Prius engines ability to stay within it's efficiency envelope.

Finally, just try and get two, 250 lb guys into the back of that BMW comfortably; it won't happen. Meanwhile Prii are increasingly used as taxis at a fantastic fuel and emisssions savings in cities where it really counts. Riding in the back seat of a Prius is comfortable.

Given the source and the lack of attention to detail I would say that this was a cheap and intentional cheat by a car writer in order to gain access to a "special favor."

Put the Carbon Back

I can almost see how it evolved.

Two guys drinking at a pub dream up a way to get an all expenses paid road trip, and three days off work. The next day they approach their editor with the idea. He buys it and off they go. Road trip!

They probably had to script it with hangovers. That scene with Jason running out of gas was funny, but for the wrong reasons.

It is entirely possible that the Beemer got better mileage, and we all know that if you stick an injected, turbo charged diesel (with advanced air pollution controls like soot traps and NOx neutralizers) in a hybrid you are going to get incredible mileage. The question is, how many people will want to pay $30,000 to get 60 mpg? To be honest, I have a feeling a lot of people would go for it. The arms race would escalate.

Turbo chargers are complex machines. High pressure injectors are prone to problems. Air pollution controls are unreliable. Add that kind of complexity to a hybrid drive train and you have created twice as many failure modes.

Picture people buying those cars to eclipse the Pious snobs only to be eclipsed by the Pious snobs in plug-ins, who are in turn eclipsed by God knows what--bubbles powered by dark matter.

Transportation has to rapidly evolve past the cars of today, including the Prius.

http://money.cnn.com/2008/03/06/autos/volkswagen_diesel_h ...


In the end, it all comes down to biodiversity. Poison Darts--Protecting the biodiversity of our world

Honda Civic

Meanwhile, on my latest road trip with a 2005 Civic I got 43 mpg. It consistently gets 37 or 38 in mixed driving. The solution to the car syndrome is smaller, lighter, slower and less frequent and more intelligent driving.

Excuse me...

Excuse me, did you say ROAD TRIP?

The real problem is not gas mileage, or Prius vs BMW, or bad journalists. The problem is people that drive for recreation. Yes, that would be people that take ROAD TRIPS. My favorite poser-enviromentalist is the one that drives 100 miles to a place to Bike-- Green bumper stickers, Prius, and all. The next best is one that FLIES to Aspen for an environmental conference.

Be part of the solution, don't drive for recreation.


well...

Actually it was a trip that needed to be done. And it was on the road. Hence road trip. But actually, look at the statistics. It's really ONLY recreational driving that we should be doing. It's the business stuff that's got us into trouble.


Counting the Deck Chairs o the Titanic

Neither the Prius or the the BMW is a sustainable form of transportation. By the time all the resources and energy required to build and maintain the vehicles, roads, parking and bridges are accounted for, I suspect any small incremental improvements in gas milage are not that significant. Improved milage also makes driving cheaper and thus encourages people to drive further.

Also note that hybrids are very efficient at stop and go driving but often are no better or even worse than non-hybrids at highway speeds.

Hybrids are the light cigarettes of the auto industry designed to convince people that driving has a future so we continue to buy cars and build highways thus delaying the needed transformation of our transportation system and our communities.

Much better to not drive at all. Live close to work, ride a bike, walk, take transit.

n

Racc:

http://news.google.com/news?q=telecommuting

Nucbuddy is right

We should look for ways to increase telecomuting. I would not be surprised to see that with no expense, we could save more energy than all the biofuel produced. Somebody do a spreadsheet.

In the end, it all comes down to biodiversity. Poison Darts--Protecting the biodiversity of our world
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