87.7 MPG Sweeet!!!

Gross estimate, the 800 foot drop saved you 300 meters * 2000 kg * 10 = 6 * 10^6 joules, or 0.28 kwh. A gallon of petrol is worth about 12 kwh of energy at the shaft, so 0.28 kwh is 0.023 gallons.

Almost there ...
You used 14.3/87.7 = 0.163 gallons of gas.
Without the help in declination, you would have used 0.023 + 0.163 = 0.1853 gallon, which works out to 14.3/0.1853 = 77.17 mpg.

Cool! Wait for a real engineer to bless the calc before crowing.

 

What's the 2000kg? If weight, the Prius weighs in at about 3000 lbs.

 

Report back when you have driven 400 miles with this tank. I can achieve over 99.9 mpg for the first 10 miles after fill up by using EV mode and going slight down hill like you said.

 

Re-check that joules to kwh conversion.

My original rule of thumb was 1 gallon per 10,000 feet, so an 800 foot drop would save 0.08 gallon. That would put his 'flat' mpg at 58.8 mpg.

Some months ago Ken from Japan, Bob Wilson, and I compared measurements for fuel vs. elevation change. I don't think any of theirs were more than 20-30% different than mine. We'll have to dig up that thread.

One of my best results was this, though it also involved a substantial drop in elevation. The really good GenII drivers can beat this on flat ground.

 

Brain fart -- I decided that one Kg is 1.5 pounds.
A more accurate (and minus calculator error) potential energy gain is
275 meters*1400 kg*10 ms^-2 = 3.85 *10^6 Joules = 1.07 kwh.

This is 0.089 gallons at the driveshaft, close to fuzzy1's estimate.

 

LOL!

A few of us could probably be in that Intel commercial where one engineer converts a minus to a plus ... and the rest of us roll on the floor laughing our asses off ... while our better halves roll their eyes. <GRINS>

Bob Wilson

 

the only thing that counts is what you get per tank...Period:_

 

You must drive on a complete flat roads and lots of down hills to achieve that mileage. I thought I was doing good with my first tank (240 miles) @ 49 mpg.

 

I can remember geting similar results when mine was new and the first great feelings it brings. It is very hard to keep it at that level as your mileage progresses. But it "IS" a lot of fun trying.

 

Thats great mileage, but up here in colder climates with Ethanolized gas, those figures are close to impossible.

I got over 57 MPG, calculated by miles driven and gas used, in September. Our last tank was only 47 MPG with colder days, wet roads, and winterized/ethanol gas.

Also I believe you have gas with no Ethanol, which will easily get you 3-5 MPG's more.

It sure is amazing the amount of difference people are getting in MPG, you will never see that difference in regular cars.

alfon

 

You might want to look at the user mileage records at:

Fuel Economy

Bob Wilson

 

On a percentage basis, even nonhybrids have a huge spread.

 

Your numbers are obviously very impressive. Not that I am doubting but, I am curious how you are getting these numbers.

Could you please describe your driving procedures for the rest of us 45 to 47 MPG (on average) people?

 

Proof ?

Energy calcs certainly don't support your assertion, since with E10 you are only diluting the total energy content by ~ 3.3%

 

I'm not going to check your numbers or conversions, but I do believe that you neglected to include efficiency losses, which are quite substantial when dealing with an ICE gasoline engine and all the mechanical and air friction losses of the vehicle. The efficiency losses would theoretically result in added fuel savings for the fuel you didn't use due to elevation drop.

 

Which numbers to you want to get? My 84.6 picture was a response to the VW TDI Tank Wars challenge. To replicate that, I suggest:
(1) Wait until warm dry weather returns;
(2) Find some non-ethanol fuel;
(3) Fully inflate your tires;
(4) Drive to the top of a mountain;
(5) Reset the Trip meter;
(6) Keep your speed down;
(7) Take it from there.

If 50-55-60 MPG numbers are sufficient, I would start with these links. First, here on PC:
New Owner? Want MPG help? Read this first.

After that, try the Basic and Intermediate methods from a Hypermiling site:
Beating the EPA - The Why’s and How to Hypermile
Pulse and Glide plus Warp Stealth in the Prius II

However, if your local traffic culture requires speeds above 65, then you may be stuck with your current MPG.