Most fuel efficient speed (highest MPG)?

[F8L]

Originally Posted by CharlesJ

I am not a fast driver, don't approach the limits much and haven't gotten to 50 mpg yet for a tank. Sure, on some 5-10 min segments I have seen that 100 but not overall tank.

So many people focus soley on the speed....

You need to work on anticipating stops and letting off the gas pedal and gliding for as long as you possibly can. Do this on country roads and you will see a big jump in milage. I also do this on residential streets. There are MANY cases where you can accelerate from a stop sign and just lift the gas, reapply a bit of pressure and glide to the next one. Most people just accelerate up to speed then sit there with their foot on the pedal and the ICE running then start applying the brake for the next stop. This is very inefficient.

I used to never get over 50mpg but once I started playing around with gliding to stops from as far away as possible my milage shot up and getting 51-53mpg was realitvely easy. I would need to P&G to get over 55mpg though.

All that changed when I swapped to new tires and changed my commute which now inclused a 2,000 elevation gain every day.

[GreenJuice]

Originally Posted by donee

My experience with such low speed P+G's is that I cannot get the car to kill the engine... Are you using the temperature sensor hack ?

Originally Posted by Shawn Clark

Yep, this is what I observe as well. I go ahead and take it up to 35 for the reasons you stated, then let it fall to 25 in the glide before repeating.

I didn't know that the ability to P&G is limited at low speed, and also overcome by reaching higher speeds. Is this limitation only observed when not in Stage 4?

[bestmapman]

Originally Posted by donee

Hi Best...,

I have to give that a try.

My experience with such low speed P+G's is that I cannot get the car to kill the engine. If the engine stays on during the glide, I am lucky to get 55 mpg. If the top speed is above 35 mph the engine will kill, but not always, depending on the warme up / thermos bottle recharge cycles in the car. In fact, I cannot be confident it will kill the engine below 35 mph until I am 1/2 mile from the destination. I cannot be sure the car will kill the engine for a glide above 35 mph, until I am about 10 miles into a route when the temp is 60 or warmer. This became very apparent with the MYCANSCAN, as the tachometer would stay green rather than go black, when the glide attempt was made.

Are you using the EV switch to kill the engine after pulsing ? Are you using the temperature sensor hack ?

IF you are not getting into stage 4 if you have not hit 157F and you do the idle check stop. If you are not in stage 4, then the ICE will not turn off below 34MPG.

Yes I have and EV switch and and EBH and I use the EV switch to kill the engine in stages 2-3. This helps tremendously. The EBH lets me start with 125-135F at startup.

I am not using the temperature sensor hack. If you use the EBH, since I start with such a high temp, I get into stage 4 very quickly.

[SureValla]

Originally Posted by SureValla

Bob, could you explain those series a bit more than the top descriptions?

I take that back i found your other thread, my question though is where you got the 190 from.

[xsmatt81]

I still P&G when I can, often i forget though and just drive it. Came in from St.George last weekend and was going 85 on the freeway, I still netted around 43mpg. It's creeping back up towards 46 avg now with P&G and gliding. I still managed to get 479 miles on that tank with aggressive driving. I attribute some of that to the fact I used Shell gas on that tank, my mpg always shoots up easily when using Shell gas. The prius loves it, the new Nitrogen enriched stuff seems even better.

driving 50 in a 65 is dangerous around here, likewise going 25 in a 45 is really bad, and will probably get you a ticket. The only time I P& G are on side routes, off the main drags.

[SureValla]

if anything shouldnt the Nitrogen decrease gas milage b/c the gas then has a lower % of gas in it and thus a lower energy content?

[bwilson4web]

Originally Posted by SureValla

I take that back i found your other thread, my question though is where you got the 190 from.

Ken@Japan found it in a Japanese web site. This is the rolling drag used for the NHW11 Prius, the model I drive.

Folks have been using one of two formulas to express the vehicle performance:

• Drag_force = rolling_drag + (Cd*A*p*(v**)) ## traditional
• Drag_force = C + (B*v) + A*(v*v) ## EPA approach

rolling_drag - treated as a constant
Cd - coefficient of drag for vehicle
A - cross-section area of vehicle
p - air density
v - velocity

C - fixed drag force
B - drag force proportional to velocity
A - drag force proportional to velocity squared

Bob Wilson

[richard schumacher]

Originally Posted by SureValla

if anything shouldnt the Nitrogen decrease gas milage b/c the gas then has a lower % of gas in it and thus a lower energy content?

For all we know it's more energetic than gasoline, but in any case it's a trivial amount of material and will have no significant direct effect on MPGs. Even E10 is only 3% less energetic than gasoline, gallon for gallon.

[SureValla]

Originally Posted by bwilson4web

Ken@Japan found it in a Japanese web site. This is the rolling drag used for the NHW11 Prius, the model I drive.

interesting b/c I have my own version of your spreadsheet I made some time ago and I use 144 N for the rolling drag

F = mg*mu

m = mass = 1398 kg
g = accel of grav = 9.81 m/s^2
mu = coefficient of friction = 0.0105

I forget where I found the 0.0105 but is the difference in the equation.

[bwilson4web]

Originally Posted by SureValla

interesting b/c I have my own version of your spreadsheet I made some time ago and I use 144 N for the rolling drag

F = mg*mu

m = mass = 1398 kg
g = accel of grav = 9.81 m/s^2
mu = coefficient of friction = 0.0105

I forget where I found the 0.0105 but is the difference in the equation.

I can believe it is lower for the NHW20 due to the lower transaxle drag. Pump the tires to max PSI and you're there.

Bob Wilson