Pulse and Glide (Hypermiling trick)

[donald1]

This sounds like what the grand kids and wife have ben accusing me of the last twenty or so years. They call it driving like an old man. (71)

[mmmeat]

Originally Posted by unicycle

I drove my usual route into Manhattan today, but this time I tried the pulse & glide technique I'd just figured out from a hypermiling website. It seems to have worked.

P&G
Basically this technique calls for choosing some optimum speed, say 65, and gently pulsing up to about 5 mph above that before gliding back to a speed about 5 mph below it. In this case, a person would be ranging from 60-70

It's well known that one of the hallmarks of drunk driving is the inability to maintain speed.

Also, pulse and glide is a hypermiler technique for vehicles like the Chevy Tahoe Hybrid or the Prius; vehicles that turn their engines OFF. The Smart doesn't do this, so you will continue to use gas during the 'glide phase' anyway.

I would truly hope that you do not exhibit this behaviour in front of police officers or other drivers who may be following you. It's pretty rude.

Your pal,
Meat.

P.S. I did get to drive a Tahoe Hybrid up to Big Bear and back down the mountain. It got 20 MPG up the mountain and 34 MPG back down the mountain. While my opinion of the Tahoe Hybrid is favorable, I continue to believe that the only reason Priusii exist is to cause traffic jams.

[Kermit]

P&G Coast - I use it on our gradual hills around here when there are no cars behind me. Helps a lot when I need to recover my mileage like this tank. I let a friend drive around the block (with me in car) and he killed my mileage.

P&G - I do it, but not extreme.

Others who have witnessed me driving had mentioned "I've noticed you zipping around, that car seems pretty quick" so from others observations I guess I don't hold up traffic but still am getting extremely acceptable mileage. I just fall into the definition of hypermiler (GasSavers.org - Fuel Efficiency, Save Gas and Gas Mileage Forum)

[unicycle]

Originally Posted by WhiteNBlack08

If I was driving near someone who was doing this, I'd probably run them off the road. Talk about inducing road rage, that would do it in a hurry.

Well, if it's any consolation, your post gives me forum-rage, but don't worry -- I won't byte you.

Actually, as usual, the people who mention this topic (rage) have only briefly glanced at what I wrote about NOT doing this when there are cars behind me.

And another point: Is your rage induced when you come upon a driver going 5 mph less than the speed limit? That's my average speed, with or without P&G or P&G Coasting.

I should mention that I've driven nearly 8000 miles in just over 2 months and have only received waves consisting of all five fingers from passing cars -- never the 1 finger wave that I'd get if I did this in heavy traffic.

Most normal people simply pass me if they feel I'm going too slow for them. That's what the passing lane is for.

[madbunny]

I've started using a variation of this down some of the steeper hills, but I don't have any data to see if it actually helps. I'm only doing a 3-5 mph variation, but with my foot off the gas and it still in drive, the injectors are shutting down after a second or two. Mostly I'm doing it in situations where I'm so close to letting my foot off the gas anyways that once in while I would accidentally let off enough and get the heavy engine braking anyways. Now with this technique it's more deliberate...and I thought it might save some gas.

[Smart Enuf]

Originally Posted by unicycle

Right, and that sort of issue is addressed at the HM sites -- you can't do these sorts of things with drivers all around you and only two lanes, for example, if only because it causes them frustration, wastes (their) gas, etc. The conditions need to be ok.

But as for the concentration, that's not a good point, really, unless the driver is mentally impaired. You don't need to be looking at the speedo, really, in order to have a good sense of how fast you're going. In fact, most of us (since we don't have cruise control) would have to gauge our speed by listening to the motor, or looking at other cars, or checking out the speedo. Shifting into N and back to D takes little thought -- tho you have to be careful not to try to shift into N when you're already there -- then you'd be pushing towards R (tho the car shouldn't allow that to happen). So as a precaution, I leave my right hand on the gear shifter. I can't imagine it takes my mind off driving too much. On the contrary, I've found that the extra concentration causes me to be much more alert, and that makes me a much safer (and more awake!) driver. Sometimes on my long drive I get tired, and this keeps me focused and makes the miles drip away so that I seem to be getting home faster (that is to say: time flies). So I advocate this technique for most ppl.

Hey, if it works for you, then fine. But many, if not most, people underestimate how much concentration it takes to do seemingly simple tasks. Simply talking on cellphones, which physically requires no more than holding the phone to your ear, has been directly linked to many accidents. There are studies that show focusing on the conversation, rather than the physical holding of the phone, is what causes the loss of concentration and resulting accidents (hence the illogic of handsfree laws). Pulse and gliding would seem to take at least as much brainpower, whether you're conscious of it or not.

And I have seen hypermilers attempting this technique on busy freeways (not congested, but just lots of cars), so it is a real concern for me. Plus, even on a less busy road, unexpected things can happen very quickly, so saying you only do it on clear roads isn't a real good argument either.

My point is this: Driving is one of our most serious privileges, and we need to take it seriously. It is one of the few things most people do everyday that can actually injure or kill another person. Given this, why would you take even the smallest chance of possibly injuring or killing someone by not applying 100% of your brainpower on the task of driving defensively? And doing so just to save a few mpg for yourself?

If saving the environment is your goal, you would be better off helping to lobby Congress to change the CAFE standards to encourage a lot more micro cars like the smart or other fuel miserly cars, so that a lot more people are saving gas by driving normally rather than a few people going to questionable extremes like hypermiling.

[mmmeat]

Originally Posted by unicycle

Actually, as usual, the people who mention this topic (rage) have only briefly glanced at what I wrote about NOT doing this when there are cars behind me.

Well, before you whip out your Righteous Indignation over the real or imagined failings of others, let's revisit your original post...

Originally Posted by unicycle

I drove my usual route into Manhattan today, but this time I tried the pulse & glide technique I'd just figured out from a hypermiling website. It seems to have worked.

P&G
Basically this technique calls for choosing some optimum speed, say 65, and gently pulsing up to about 5 mph above that before gliding back to a speed about 5 mph below it. In this case, a person would be ranging from 60-70.

P&G + Coasting
Since our smarties are so quick to decelerate via the engine, you can extend the glide by shifting into neutral as soon as you hit your optimum+5 speed. This simply prolongs the glide and forces you to pulse (accelerate ) less often.

Anyway, I didn't make any other adjustments to the car before the trip (more on that soon), and I found by the end of the ride that, according to my SG, I'd avg'ed over 55 mph for the trip and had used only 1.45 gallons for about 80 miles (normally the trip uses up a bit more like 1.7-1.75 gallons).

My next step is to inflate the tires to 43 psi in order to see if there is yet another gain in mpg's.

...and you show me where you mentioned anything - anything - about "NOT doing this when there are cars behind me."

Admittedly, you do mention this AFTER others have said something about it, but you did not say anything at all about it in your original post. Your bad, not others.

Originally Posted by unicycle

And another point: Is your rage induced when you come upon a driver going 5 mph less than the speed limit?

Err ... You're disrupting the flow of traffic (repeatedly) by 10 MPH, not by '5 mph less than the speed limit.' Get your facts straight.

Your pal,
Meat.

[bull8042]

DANGIT mmmeat! There you go again, killing another thread!
Dude, you are good...

[mmmeat]

Originally Posted by Smart Enuf

(hence the illogic of handsfree laws).

While the logic used by states like California to get to the handsfree laws is thready and stupid at best, I tend to look at hands free this way:

If someone is driving along drifting around the lane, nudging other cars, speeding up and slowing down then other drivers are going to react in one of two very distinct ways:

1. If the other drivers see an idiot on a cell phone, they're going to get angry and road ragey on his butt.

2. If the other drivers see someone driving along talking to empty space, they're going to leave him alone. You don't mess with crazy people that talk to themselves.

Your pal,
Meat.

[mmmeat]

Originally Posted by bull8042

DANGIT mmmeat! There you go again, killing another thread!
Dude, you are good...

It's my job. It's what I do.

Your pal,
Meat.