P&G EOC gains 20% mpg on the highway

[PaleMelanesian]

I've previously tested this car and it does 50 mpg @ 50 mph with cruise control on a flat road.

This weekend I drove 60 miles each way on the highway with 3 passengers outbound and two returning. I ran mostly steady speed (but some strategic speed variance and downhill coasting) going out. Occasional AC and hills and light traffic roughly countered the mild techniques I used. I did full P&G EOC coming back. Both runs averaged 50 mph by the Scangauge (on purpose).

Out: 49.7 mpg @ 50 mph
Back: 60.2 mpg @ 50 mph

Same average speed, P&G EOC gave me 20% better mileage.

[Diesel_Dave]

What speeds did you P&G to? I understand average was 50 mph, but did you pulse from 40 to 60 mph, 45 to 55 mph, etc.?

[PaleMelanesian]

Mostly 45-60 mph, but with certain moments higher as the rolling hills and/or traffic waves dictated. I held a minimum of 45 for safety.

[Daox]

Well that pretty well proves that P&G does in fact work pretty darn well on the highway.

[PaleMelanesian]

It works particularly well on a car like this that runs 2900 rpm at 60 mph. I'm sure if the gears weren't so stupid, steady speed would be closer.

[HypermilerAX]

Yep, P&G works great whenever engine load is low. A powerful, aero and short-geared car will work best. An underpowered car and/or with very high gearing will work less.

My AX's engine, with its neverending final gear, it at 50% load (2000 rpm) at 56 mph and 72% load (2500 rpm) at 70 mph. That puts me quite in the sweet spot. I only P&G with a strong tailwind or on downhills >1%, enough to lower the load to make P&G interesting.

[MetroMPG]

Originally Posted by HypermilerAX

A powerful, aero and short-geared car will work best. An underpowered car and/or with very high gearing will work less.

I can confirm this too with the Firefly/Metro and its taller final drive. The P&G highway advantage is much smaller.

Which is fine with me, because I prefer to just cruise (drive with load/target drive) on highway trips. (Though I still use it strategically depending on terrain, speed zones, etc., on a given trip.)

[Diesel_Dave]

Yes, P&G will definitely help more on an overpowered vehicle (such as my truck).

If you want proof that EOC P&G saves fuel I recently measured my idle fuel rate and found it to be slightly greater than my average fuel rate during my commute. So if my truck were just setting on a trailler idling while being pulled by another vehicle it would actually burn MORE fuel than I typically do driving with EOC P&G.

[PaleMelanesian]

I hadn't thought of that angle before. It holds true with mine as well. My warmed up idle consumption is about equal to my average trip hourly consumption. Since I'm starting each trip with a cold(ish) engine, I'm doing better than I would just idling.

[Gasoline Fumes]

Originally Posted by MetroMPG

I can confirm this too with the Firefly/Metro and its taller final drive. The P&G highway advantage is much smaller.

Which is fine with me, because I prefer to just cruise (drive with load/target drive) on highway trips. (Though I still use it strategically depending on terrain, speed zones, etc., on a given trip.)

I'm pretty sure highway P&G hurts my MPG. I can't coast far enough to recover from the long pulse. Cruise and glide works much better when the hils are where I want them.