just found this from last November - could not find any mention of it on gh.com. Some of the newer members might like this information:

http://www.edmunds.com/advice/fuelec...2/article.html

 

With almost a third of a million hybrid vehicles in the US, one could estimate how much fuel is getting saved overall. But if even a moderate proportion of 'regular car' drivers would utilize the often printed fuel economy tips, I believe that those fuel savings would be greater still. There is room for all to help out with this oil consumption problem.

DAS

 

Worth keeping in mind that their results for A/C are probably correct for most non-hybrid cars but may not apply to many hybrids. As has been noted elsewhere, for cars with more powerful ICE's burning more gas the additional load from A/C may be an insignificant portion of the total energy expenditure. [I wish the article mentioned which vehicles they used!!] But hybrids with smaller less powerful ICE's burning much less gas may suffer a big hit in mpg when the A/C is on. This is definitely true for my Insight [10 mpg drop is frequently quoted] but I'm not sure how much HCH's, Prii, FEH's and TCH's are affected.

I apologize if this has been discussed at length in other threads.

 

To the extent the only difference is that the AC is a larger percentage of engine power on the hybrid vehicles, it's not clear that the actual cost of running AC is different for hybrids and non hybrids -- these article should discuss these sorts of issues in those terms. Cooling a Civic for example will require the same amount of energy be it a hybrid or a non-hybrid. The relevant figure should not be "how much does this hurt MPG (dependent on hundreds of factors)" but "how much does it cost per hour to run air conditioning".

It will probably be slightly worse on the Hybrid, in absolute terms, if you already have a heavy driving load -- such as going up an incline on the highway as it will force the smaller engine to rev up to a higher RPM, and thus incur efficiency loss, while an oversized engine might go from being underworked, to a more efficient engine load. But I expect this difference to be minor. The main differnece is that a given gallons/hour to run AC represents a lot more "MPGs" if you're in an economical vehicle.

Another point of note about this is that a hybrid drivers attempting to maximize mileage by driving slower will see an even greater hit from AC, in absolute terms, as they will be out on the road longer. (Although most in that category use AC sparingly or not at all) Finally, the fact that the hybrids have aerodynamic, sloping windshields will hurt them more for AC as well, as this will generate much more solar heating than a car with more vertical windows.

The fact that the new EPA test will require air conditioning/vehicle cooling as part of the driving cycle is good. It means that carmakers will have an incentive to do things like come out with Infrared blocking windshield glass, better heat insulation, better circulation, and more efficient air conditioners on cars.

 

Forget most of the tips, most drivers could see a massive increase in fuel economy just by not driving 75 MPH and instead driving 65 MPH. The other tips are good too, but merely reducing speed can help a lot. Going down to 55 MPH gets you even better MPG.

The reality is most drivers have plenty of avenues open to them to increase their MPG. But it's easier for them to just drive however they want, and then ***** about high gas prices and greedy oil companies, etc.

Anyway, the way I see it, it's only a matter of time now before the 55 MPH limit returns, so why not get used to it now, and save gas while you're at it?

 

Good point. A lot of work is being done in this area and there are some vehicles on the road today with iead impregnated windshields that help block IR. Better (or at least alternative) ways of blocking IR are being researched because lead also blocks IR going out, which will negatively impact several technologies being developed to make the driving experience safer.

Peace,

Martin

 

What utility is there in IR leaving the cabin?

 

I think what he means is that you want heat coming from the cabin (e.g. the batteries and computers) to be able to escape. An IR-reflecting coating on the windows will not only reflect IR coming from the outside back to the outside; it will also reflect IR from the inside back to the inside. An excellent point.

 

Camera based technologies for pedestrian detection / obstacle detection / road condition / lane departure warning. Some of the cameras will not work well with lead impregnated windshields.

Peace,

Martin

 

I've been posting great tips there since mid 2004. My tips were generally squashed by members there and staff as well, especially a "Mr_Shiftright".

At one point I admitted to shutting off my engine on a familiar abandoned rural road at 3:00AM going 20-35MPH on almost level ground and rolling gas-free for over two miles.

Edmunds staff comment:
Notice how they take their own very poor judgement which has nothing to do with what I described, then relate his dangerous actions to my own.

That is only one of many examples over the years.

Funny that while the Katrina fuel crisis was in its peak I posted tips there again only to get the same reaction from the staff....
Except for one driver: a Lincoln Navigator of all people raised his MPG from around 19 to 28 for two consecutive tanks!

I don't believe Edmunds staff has any fuel economy thoughts in them what so ever, but rather what is big, powerful and 0-60 in shortest time.
Bet they'd rate the Prius or HCH at 25MPG if they could get away with it.