Engine Braking and Fuel Economy

[insite]

either way, we're splitting hairs here. modifying your driving one way or the other would probably result in near immeasurable differences in fuel consumption.

wanna save fuel? drive with your top up, inflate your tires to 36psi, go slow on the freeway, and accelerate at a boring rate. me? i bought a porsche precisely because i don't like to do ANY of those things (except keep the tire pressures proper)

[BoxsterLewis]

Are you guys really wanting to save a couple dollars of gas here? It seems to take more work to attempt to do all the things then just to drive freely. Gas has gone up 1.00 in the past 6 months and thats another 16 dollars per fillup, i think you guys make enough $$$

[Brucelee]

How much is perrier per gallon, how about a Starbucks latte.

Folks are funny around fuel prices.

[Brucelee]

BTW- I asked this question last year.

How much SHOULD gas cost and how do you know that?

:dance:

[Lil bastard]

Originally Posted by Brucelee

BTW- I asked this question last year.

How much SHOULD gas cost and how do you know that?

:dance:

According to the API, it costs about $60/bbl. to drill, pump and refine a barrel of crude from on-land and coastal-water rigs and upwards of $90 for deep-sea rigs.

One barrel of crude equals 42 gallons. This will yield 47% (19.7 gal.) gasoline, 23% (10 gal.)heating oil and diesel fuel, 18% (7.5 gal.) is refined to other products including petrochemical feedstock such as polypropylene, 4% (1.7 gal.)propane, 10% (4.2 gal.) jet fuel, and 3% (1.26 gal.) asphalt. (Percentages sum to over 100 because there is approximately a 5% processing gain in refining.) - source: Energy Information Administration - http://tonto.eia.doe.gov/ask/crudeoil_faqs.asp

[Brucelee]

Originally Posted by Lil bastard

According to the API, it costs about $60/bbl. to drill, pump and refine a barrel of crude from on-land and coastal-water rigs and upwards of $90 for deep-sea rigs.

One barrel of crude equals 42 gallons. This will yield 47% (19.7 gal.) gasoline, 23% (10 gal.)heating oil and diesel fuel, 18% (7.5 gal.) is refined to other products including petrochemical feedstock such as polypropylene, 4% (1.7 gal.)propane, 10% (4.2 gal.) jet fuel, and 3% (1.26 gal.) asphalt. (Percentages sum to over 100 because there is approximately a 5% processing gain in refining.) - source: Energy Information Administration - http://tonto.eia.doe.gov/ask/crudeoil_faqs.asp

That MAY be the cost of procuring the oil to gas. The second question is how much should it sell to us for?

[Chills]

Without reading any of these responses I will say that I tested this out the other day.

I filled up my tank and then reset the onboard computer to check my MPG.

It is only 1/2 a mile from the Shell to my house so while driving home I blipped the throttle when downshifting and braking and I watched as the MPG numbers went WAY down. It was 19.2 and dropped to 15.4 by the time I made my final turn into my garage.

When the RPMs go up the MPG goes down.

[Lil bastard]

Originally Posted by Brucelee

That MAY be the cost of procuring the oil to gas. The second question is how much should it sell to us for?

OK now you open up a whole new can of worms...

Crude Oil is traded as a commodity and therein lies the problem. As a commodity, it's price is based primarily on Investor Confidence - confidence that an Investor can buy it and then later sell it at a profit !

Geo-political environment and events play a much greater role in establishing this Investor Confidence than do Supply and Demand (though these too play a lesser role).

Having it commodity-based allows for much greater manipulation of the price than if it were simply a raw material bought and sold as such. There is no way of setting a price of how much it should cost us... only what we're both willing and able to pay.

[RandallNeighbour]

Originally Posted by BoxsterLewis

Are you guys really wanting to save a couple dollars of gas here?

Not me! I started the thread because a friend of mine is emphatic about coasting with brakes vs. engine braking for fuel economy's sake alone and I completely disagreed with him on the basis of sound logic.

I wanted some empirical data to back up his claim or mine so I could settle the argument.

Still haven't seen any yet. Great discussion and more sound logic to bolster my position in this disagreement, but no empirical data (charts, testing, results, etc.)

[Samson]

You could just buy a ScanGauge II and find out exactly when fuel is and isn't being delivered (along with a bunch of other info).
http://www.scangauge.com/

[Houston C4S]

Randall,

You could just ask me...

- Mark

[RandallNeighbour]

Originally Posted by Houston C4S

Randall, You could just ask me... - Mark

Great! You've got my email address... shoot me a copy of the empirical data on engine braking and the effects it has on fuel economy in your possession.

Opinions based on sound logic have already been shared, so there's no need for any more. I want a published study by a reputable source. Got one?

[SoCalKen]

Originally Posted by RandallNeighbour

Not me! I started the thread because a friend of mine is emphatic about coasting with brakes vs. engine braking for fuel economy's sake alone and I completely disagreed with him on the basis of sound logic.

I wanted some empirical data to back up his claim or mine so I could settle the argument.

Still haven't seen any yet. Great discussion and more sound logic to bolster my position in this disagreement, but no empirical data (charts, testing, results, etc.)

Having said that I agree with your friend. With your car in neutral you will start coasting sooner resulting in less fuel usage. End result you will probably be off the gas and coast for 3000 yards vs. waiting to engine brake and be of the gas for only 2000 (coasting numbers random) yards. I don't believe it's the actual braking process but the habits associated with it, ie: initiate fuel saving coasting earlier.
Ken

[Wret]

Originally Posted by insite

either way, we're splitting hairs here. modifying your driving one way or the other would probably result in near immeasurable differences in fuel consumption.

wanna save fuel? drive with your top up, inflate your tires to 36psi, go slow on the freeway, and accelerate at a boring rate. me? i bought a porsche precisely because i don't like to do ANY of those things (except keep the tire pressures proper)

Good point.

If you want your paint to last longer, don't wash it.

If you want your car to last longer, don't drive it.

If you want fuel economy, find an old Geo Metro.

If you want to have fun, step on all the pedals all you want.