consumer reports hypermiling blog

[rigormortis]

09/12/2008

Hypermiling – Evaluating common fuel-economy tips on the road

In "Hypermiling - The new menace on the road?" I wrote about drivers who compromise safety and traffic flow in an effort to get the most out of a gallon of fuel. And while some people may employ annoying or even dangerous hypermiling techniques such as driving 45 mph on the highway, turning the ignition key off when coasting, or tailgating a big rig for aero, many people are just looking for a safe and effective way to save fuel.
Some of the responses to my previous blog encouraged me to research and report more on hypermiling. I went to cleanmpg.com for information from the "mild" to "advanced" ways to hypermile.




Hypermiling ? Evaluating common fuel-economy tips on the road: Consumer Reports Cars Blog

[miscrms]

Thanks for posting!

Submitted the following comments, we'll see if it gets published.

Thanks for taking the time to go beyond the sensationalist hype and take a more serious look at this topic. There are people who take hypermiling too far, but the vast majority are pretty sensible about it. I would also have to interject that most of the conditions under which hypermilers are deemed rude or dangerous have more to do with other people driving like idiots. If you try to drive the speed limit these days people will practically run you off the road. How dare you obey the law! If you try and drive efficiently between lights people get all annoyed and go racing around you, only to end up sitting at the next light right next to you. IMHO hypermilers aren't generally the problem, they are the ones trying to be reasonable.

All of the tricks you mention above work almost as well on a normal car as they do on a hybrid. The Prius does have some attributes that make it particularly well suited, but that is not a requirement. P&G is helped in the Prius because the engine shuts off, but works in all cars due to the efficiency curve for a gasoline engine. The engine is least efficient at very light loads, like cruising steady at low speeds. By Pulsing, you push the engine into a more efficient operating region, and then by gliding use as little fuel as possible in between pulses. I would have to disagree with the previous poster though. At WOT (wide open throttle) efficiency drops off and emissions go way up as the engine control goes open loop. About 1/2 to 3/4 throttle is optimal in most vehicles to my understanding.

I live in an urban environment, so P&G isn't really an option. Still, by using the rest of the basic tricks outlined above I've taken my commute from 45mpg to 65mpg. Thats about a 30% reduction in consumption. If everyone were willing to make this simple sacrifice, we would have a substantial reduction in our foreign oil imports today rather than 10 years from now when CAFE standards and more efficient vehicles come into play.

Rob

[SageBrush]

Very well said, Rob.

On my way home today a caddy tried to pass me going uphill. Both I and the car coming the other way had to go on to the shoulder so that the caddy did not cause a head on collision. I was going 51 mph, speed limit 50. It was just sheer luck that none of the many cyclists who use this road were caught up in the stupidity.

I expect the caddy driver is ranting that a 'damned Prius' almost caused a wreck this morning.

[statultra]

"Forced Auto Stop (FAS)"

This is not a Honda, im not even sure why they used this term, Auto Stop refers to the IMA system Auto Stop feature.

[MSantos]

The article is OK in most areas except in its attempt to imply that tailgating large trucks is a hypermiling technique. It is not, and it is very unfortunate that there are still folks who insist on making that connection. Such attempts at connecting the two are almost as ill informed and sad as the act of tailgating itself.

Because a great deal of the hypermiling toolkit was derived from the principles governing the earlier hybrids, FAS (Forced Auto Stop) is an adaptation of the user induced engine shutdown on the Insight that became applicable to non-hybrids as well. It may be helpful to remember that when the toolkit was established, the hybrid market share was barely 1% so the actraction of this technique was most useful for the other 99% of the drivers out there.

Cheers;

MSantos

[Rybold]

Here in Southern California, in Orange County, all of a sudden in the past few weeks, the flow of traffic is accelerating and braking much more gradually and driving slower. This is very ironic to me since gas prices are now going downward. (Yes, those who follow the commodities exchanges know there is a direct relationship between consumption (supply/demand ratio) and prices, but I don't think your average citizen cares so much as to conserve fuel even as gas prices are down $1.00 from their highs and still falling (peak here was $4.79/gal and right now it is $3.65/gal). With everyone driving more "conservatively," people here are now much more tolerant of semi-hypermiling. Many times, to my complete astonishment, I've looked in my rear view mirror to see that the person behind me was in complete approval of my driving habits (and the cars behind him didn't seem to mind either). I drive a lot and I've been seeing this all over Orange County.

[miscrms]

Seen it here too, still plenty of aggressive drivers but on the whole things are much different than they were a year ago.

[john1701a]

Originally Posted by MSantos

The article is OK in most areas except in its attempt to imply that tailgating large trucks is a hypermiling technique. It is not, and it is very unfortunate that there are still folks who insist on making that connection. Such attempts at connecting the two are almost as ill informed and sad as the act of tailgating itself.

Correct, it IS not. But back when the term was first coined many years ago, it WAS indeed. Outdated references are a reality those supporting hybrids just learn to put up with. After all, the word "hybrid" itself use to mean something different too.

.

[hill]

mortis is way too hung up on the incorrect notion of dangerous increased tire inflation, falling for many of the old steriotypes and traps that the tire industry puts forth, simply to sell more product. One of the opinions laid out on the blog was from an airline pilot, telling how much more advantageous it is to have the tires pumped up nice and firm on landing. Hopefully that'll cause 'im to do a little more homework.

[rigormortis]

i didnt say it was dangerous. my only opinion about increasing ones tire pressure to the max pressure on the sidewall is looking at it, i dont think i have any chance of actually getting anything from my tire warranties, cuz it looks like it might cause accelerated wear in the middle.

and i suppose i could get a ticket.

thats all. im not hear to preach anything else.

i can't afford to do any more homework, because these 195x55x16 michelin pilot primacy tires which i am running now cost me about 800.00 to mount and balance and since they do not have any kind of treadwear warranty on them anyway, i can't afford frequent prius touring sized tires changes, you people with the base prius are lucky, you can buy tires anywhere, while us touring owners are stuck with 5 brands

i did not really mean to imply at any time that this is dangerous.