P&G, Engine On Coasting

[trollbait]

Priuses make hypermiling easy.

[FrugalFloyd]

Low&Slow and I got together with another hypermiler to test P&G with his 3 liter AT Jaguar. We hooked up my Scangauge and did four runs on a 10 mile test loop.

First run was with cruise control at 35 mpg. Vic got 30.4 mpg.

Second run was DWL at roughly the same speed. He beat CC with 31.5 mpg.

Third run was P&G, with light acceleration keeping his engine below 1600 rpm. I think we were all surprised when Vic only got 30.7 mpg.

Fourth run was combining DWL and NICE-on coasting, which should have been the best of both worlds. It was not to be. I don't remember the final run's mpg, but it was short of 31.5 mpg - probably close to 31 mpg.

We did the testing with an uncalibrated Scangauge set at 18% correction. It correlated pretty close to the iFCD in the Jaguar, and was accurate enough for comparison purposes.

[theholycow]

Did you record average speed for each run?

Perhaps his automatic Jaguar is more like the trucks Jay and I have, where you have to accelerate somewhat aggressively for the best fuel economy. If I'm too light on the go-pedal trying to keep the RPM down, I lose FE.

Anyway, every car is different, so it's always important to measure your results before and after rather than just going with a technique (or modification) without proof.

[FrugalFloyd]

No, I was resetting the Scangauge between tests, and didnt record average speeds. Three of the four runs kept speeds close to 35 mph, though. Only the P&G test was significantly slower, and it didn't show any fuel economy advantage. Next time we get together, we'll have to try harder acceleration.

[low&slow]

Hi,
Using our new-found knowledge from testing my car, I just logged a 31mpg tankfill. I used DWL and DFCO coasting to achieve this. I think i know why NICE-on coasting wasn't effective: once I shift to neutral the RPMs increase a high enough speed to rev-match back to drive. MY RPMs are less just using DWL or DFCO. Darrell is the man!
L&S

[spotaneagle]

Originally Posted by SentraSE-R

Low&Slow and I got together with another hypermiler to test P&G with his 3 liter AT Jaguar. We hooked up my Scangauge and did four runs on a 10 mile test loop.

First run was with cruise control at 35 mpg. Vic got 30.4 mpg.

Second run was DWL at roughly the same speed. He beat CC with 31.5 mpg.

Third run was P&G, with light acceleration keeping his engine below 1600 rpm. I think we were all surprised when Vic only got 30.7 mpg.

Fourth run was combining DWL and NICE-on coasting, which should have been the best of both worlds. It was not to be. I don't remember the final run's mpg, but it was short of 31.5 mpg - probably close to 31 mpg.

We did the testing with an uncalibrated Scangauge set at 18% correction. It correlated pretty close to the iFCD in the Jaguar, and was accurate enough for comparison purposes.

hate to sound like a ney sayer but 40mpg in a jag? I doubt it, unless you do some aero mods, but its a jag I doubt you will. Tire pressure? I've been trying something the last few days that seems to work well, I have my back tires at 40psi almost and the front at 32, to help handling, feels real tight around the corners still, I think I may have found a winner.. I like the way it angles my car too, higher back end, like it put more weight on the turning tires maybe?, the ride feels a little higher but almost even better

Hence this is a bonus for P&Gers, maybe?, you still get the endless mileage from having high psi(in the back), but you can take the corners well and don't have to slow down there because your tire pressure is real high in the front and back..(like alot of posters talk about having done) I do have spacers on my back wheels too, 30K miles so far...(my blowing around on windy days on the highway fix)

[spotaneagle]

I guess this leads to the next question, If I remove 2lbs of pressure from the front tires do I gain the same mpg when I add that to the back instead..

so I go from 34 in the front 38 in the back(sloppy handling sorta)
to
32 in the front 40 in the back(not as sloppy)

any takers? I would think that since the back weighs alot less I would probably need more psi to keep the gains the same.. maybe 3 instead of 2..?

[Jay2TheRescue]

Jeremy did it on an episode of Top Gear, why not?

[spotaneagle]

my current tank I am at 111miles at about 3 gallons of gas and that was mostly city minus 45-50 miles or so of 45 mph average and highway driving and two times where I idled for 2 or 3 minutes, and fixed my wai a little
37mpg


oh yea my last tank(275 miles or something) was 30.68 mpg with a hardly working wai, and barely any tire pressure (30 front 34 back)that one was probably 85% city.

[theholycow]

I have found that increased pressure makes my vehicles handle better, front and rear. Any reduction from my increased pressure to the recommended pressure compromises the gained handling.