Pulse and Glide with hills

[Tango Charlie]

My thinking is that pulse up/glide down is better, because the fuel savings is achieved in the P&G technique by the glide phase. So extending or maximizing the glide would be more beneficial.
And sickpuppy has a good point about the aerodynamic penalty of pulsing down.
P&G may be an 'advanced' technique, but it's accessible immediately, unlike waiting for the weekend/spare moment to install the vac gauge to DWL.

[IndyIan]

Originally Posted by Tango Charlie

I'm inclined (sorry ) to agree with you, but let me play the devil's advocate, for the sake of argument. 'Pulsing up' contradicts the 'ride like a cyclist' mantra. It puts more of a load on the engine, further decreasing efficiency. Is the 'glide down' enough to compensate?

Just have to point out that the above isn't true all the time, or maybe anytime for some of us. If your car has the HP to stay under 75% throttle in top gear going up the hill, it is more effecient to run the engine like that than drop a gear and use 35% throttle with more rpm. I didn't believe this until I got my scangauge but it shows that to be true.

I love P&G with hills, my 50.5km commute this morning had an average speed of 71km/h with a max of 110km/h gliding down a big hill, the speed limit is 80km/h. I got 6.0L/100km, 39MPG out of an automatic 95 Neon in light traffic.

The hills allow me to P&G in some traffic and get me to work with out any extra time and get nearly 1/3 better mileage(I use to average about 30mpg on the same route). I should note that this is engine on gliding too.

I have a couple of different route options that I can use. Some with more hills but more stops as well. The route I used today has the fewest stops and is in the middle for hills and is probably my most efficient route, sometime I'll have to try the hilliest route but it will take significantly longer but it might be the most efficient.
Ian

[PaleMelanesian]

Where the bicycle analogy breaks down is when you consider BSFC. Human legs are most efficient at any range of output. Car engines have a very peaky efficiency chart - very different. Driving the terrain like a biker is good, but P&G is better, because of this fact. If the car's engine was efficient over its whole range, it wouldn't matter. Metro can probably verify this with his Electric.

[MetroMPG]

I could verify it if I had onboard energy consumption instrumentation... which I don't, unfortunately.

[PaleMelanesian]

sorry. For you and for us.