60-50mph Pulse&Glide with Draft vs. 60-40mph Pulse&Glide without draft

[Movin]

Learning how to use your kinetic energy is one of the many secrets of hypermiling and it works well in rolling hills. When you have 22 miles of continuous steep grade you want the least amount of weight possible during that portion of the trip. It seems like every extra pound costs another gallon..lol.. drafting trucks at 15 mph!! No Hypermiling secrets here!

[rmoltis]

You say that but this guy in his metro did a test with more weight and got from 53 mpg-86mpg
He said his average was about the same as with no weight.

Im not saying one is better than the other
all I was saying is that there are many more variables to pay attention to than people like too.
There's no reason to tell people their info is false because everything is relative to how you do things.

I like more weight because I can lug in lower gears without losing speed.
And I like lower rpm driving because theoretically the lower rpms you drive at the longer the engine life.
So with the lower speed I like the weight to help average out uphills since that is where I use the most fuel.
And that is all just my personal preference.

http://ecomodder.com/forum/showthread.php/adding-weight-improve-fe-15028-2.html

[mikeyjd]

You say that but this guy in his metro did a test with more weight and got from 53 mpg-86mpg
He said his average was about the same as with no weight.

Im not saying one is better than the other
all I was saying is that there are many more variables to pay attention to than people like too.
There's no reason to tell people their info is false because everything is relative to how you do things.

I like more weight because I can lug in lower gears without losing speed.
And I like lower rpm driving because theoretically the lower rpms you drive at the longer the engine life.
So with the lower speed I like the weight to help average out uphills since that is where I use the most fuel.
And that is all just my personal preference.

http://ecomodder.com/forum/showthrea...e-15028-2.html

Rolling resistance increases linearly with weight, so it takes more energy to move the car down the road, even with no braking or accelerating. Check out this Calculator to find out exactly how much.

By P&G'ing, you've increased your engine efficiency, and perhaps by enough to compensate for the extra rolling resistance.

There is only one scenario I can imagine this having a slight real world advantage. Let's say you live at sea level. And you drive to a place that is 100 or more miles away that is at a much higher elevation, more than 1000 feet. You will burn more fuel going there than coming back, assuming that all other factors are equal.

Now, if you are fortunate enough that you leave with your vehicle empty (including a half-empty gas tank) and return with a full tank of gas and a 1000 pound load in it from that higher elevation, it will work to your advantage. It's all downhill from there, essentially, no matter how you slice it.

A car with 300lbs extra cargo converts .4MJ of extra gravitational potential energy from a 1000 foot descent. 300lb*9.81m/s*1000ft - Wolfram|Alpha

With some fair LRR tires, CRR=0.010, the cargo burns up that much energy through rolling resistance every 20 miles. .01*300lb*9.81m/s*20mi - Wolfram|Alpha

If you were descending an endless slope, it must be a 1% grade for extra cargo to pull its weight at CRR=0.01. This is independent of factors like the weight of the car, cargo, aerodynamics. It depends solely on CRR.

For our cars about a third of the load at 60mph is rolling resistance. So a 3% increase in mass (here, 90lbs) should bring a 1% increase in fuel consumption on a flat road with no stops or hills. It's a small impact, but every little bit helps (or hinders).

I hope that helps. Michael~