BS: MPG City driving

Subject: BS: MPG City driving
From: Jack the Sailor
Date: 04 Apr 10 - 01:33 PM

When you think about being green, cutting carbon, all that stuff, isn't mpg misleading? Isn't more like idle time per gallon?

Subject: RE: BS: MPG City driving
From: Amos
Date: 04 Apr 10 - 01:39 PM

Some argue for gallons per mile. I don't think MPG is misleading, but perhaps insufficient.


A

Subject: RE: BS: MPG City driving
From: Amos
Date: 04 Apr 10 - 02:27 PM

It's not misleading per se but it has been argued that other metrics would serve better--one being gallons per mile.

Subject: RE: BS: MPG City driving
From: Jack the Sailor
Date: 04 Apr 10 - 02:29 PM

In Canada it is Liter/100km.

But still the car that burns nothing at a stop light goes under rewarded.

Subject: RE: BS: MPG City driving
From: Q (Frank Staplin)
Date: 04 Apr 10 - 03:49 PM

Canada needs the tax money.

Subject: RE: BS: MPG City driving
From: Rapparee
Date: 04 Apr 10 - 03:52 PM

Canada needs to better exploit its natural resources, such as oil, uranium, and mosquitoes.

Subject: RE: BS: MPG City driving
From: JohnInKansas
Date: 04 Apr 10 - 05:23 PM

If one wants to have a meaningful number, the reference should be gallons per TON-mile (or liter/100 ton-mile.

The mpg or gpm gives no indication of what is moved a mile.

40 mpg moving an 85 lb school-child is 40*85/2000 or 1.7 ton-mile/gallon.

5 mpg moving an 80,000 lb load of frozen fish is 5*80,000/2,000 or 200 ton-mile/gallon.

So that semi in front of you is about 200/1.7 = 117.65 times as efficient as your little roller skate.

John

Subject: RE: BS: MPG City driving
From: pdq
Date: 04 Apr 10 - 05:50 PM

And a freight train is even better.

Subject: RE: BS: MPG City driving
From: pdq
Date: 04 Apr 10 - 06:11 PM

Let's put some numbers on that.

"...the average works out to be 435.88 ton-miles per gallon of fuel.

Some rail lines do better. The Soo Line, which is the U.S. branch of the Canadian Pacific, operating in the upper Midwest, reported moving each ton of freight 517.8 miles per gallon of diesel fuel, on average. Lines operated by the Grand Trunk Corp. reported 510.5 ton-miles per gallon.

The national average figure of 436 miles is the highest on record, according to AAR, and a 3.1 percent increase from the 423-mile figure reached in 2006."

{2007 numbers...they go up each year do to technology improvements...the government don't got a thing to do with it}

Subject: RE: BS: MPG City driving
From: JohnInKansas
Date: 04 Apr 10 - 06:23 PM

If only we had some decent tracks and schedules, so that it didn't require 2 months to get a load from one place to the next, but in the US there are lots of things that can't be shipped by rail. The "product" doesn't last long enough in-transit to be useful by the time it can be scheduled, loaded, routed, and unloaded.

Barges are even more "efficient" than even rail; but we don't have enough water to create any new useful canals.

And neither the train nor the barge can drive up to the corner market, so if you want something edible for lunch you still need the trucks for local distribution.

The point is that the "number" you use to decide which vehicle to get really needs to include a factor to indicate how much (or little) you can do with the wheels you select.

The crime is in getting something that can do things you won't ever use it to do. (A big EGO is horribly inefficient.)

John

Subject: RE: BS: MPG City driving
From: Jim Dixon
Date: 05 Apr 10 - 02:36 PM

I don't see any advantage to using gallons-per-mile rather than miles-per-gallon.

40 miles per gallon is exactly equal to one-fortieth of a gallon per mile, or 0.025 gpm. Like switching to the metric system, it's not any more accurate and it doesn't give you any better understanding; it just gives you the same information in a different form.

Subject: RE: BS: MPG City driving
From: gnu
Date: 05 Apr 10 - 03:36 PM

The rating system doesn't matter because it's all relative. The buyer can easily do the arithmetic for their own situation. I agree that transportation cost-benefit analyses for the movement of freight must be more accurate for the determination for charge rates, but not for a purchaser of a vehicle.

As for canals, up here in the Great White North, they would only be useful 1/3 of the year if they were all downhill. Escher that.

Speaking of TGWN, I was asked yesterday what kinda fuel consumption I am getting with my new truck. "I dunno. Have to wait a while yet as it's just spring." Fact is, when it's minus freeze yer balls off, F or C or K, ya gotta let er warm up and that throws off the litREs/100km.

Subject: RE: BS: MPG City driving
From: gnu
Date: 05 Apr 10 - 03:42 PM

BTW... all that global warming is caused by the driv-thru lineups at Tim Horton's Donuts here in TGWN, winter and summer. Not to mention the obesity.

Subject: RE: BS: MPG City driving
From: PoppaGator
Date: 05 Apr 10 - 05:51 PM

MPG/City and MPG/Highway are meaningful, and entirely sufficient, when applied to passenger-car use ~ which seems to be what the OP had in mind.

The additional caveats about the relative fuel-efficiency of different options for shipping freight are interesting additional information.

"City driving," insofar as it affects miles-per-gallon in the operation of an automobile, includes a goodly amount of idling (sitting at red lights, etc.), as well as inefficient changing of speeds, etc. That's why it always registers as less efficient than uninterrupted cruising-speed "highway driving."

Subject: RE: BS: MPG City driving
From: Ed T
Date: 05 Apr 10 - 06:30 PM

"The rating system doesn't matter because it's all relative"
Especially.if you are spinning your wheels part of the year.