Pulse and Glide questions..Totally new to this

[jesse.rizzo]

If you do end up key starting it, doesn't this use quite a bit of fuel. I had heard roughly 30 seconds worth of idling. If that's true it may sometimes be better to just leave it on, right?

[SVOboy]

I've heard that too, but my fuel meter never really showed much fuel used from a key start where the engine was already warm. Still a consideration for wear and tear and difficulty, though.

[MetroMPG]

That was IWillTry's conclusion too. He systematically measured fuel consumption @ idle, and compared it to the fuel consumed performing a warm restart.

His observations (based on a 1.0L gas engine with throttle-body injection):

If you begin to extract useful work from your engine within 1 second of starting it, then the additional fuel consumed by restarting your engine is equivalent to about 0.2 seconds of idling. So you don't even need to consider how long you might be stopping for. If you're interested in reducing fuel consumption, turn your engine off whenever you can, and don't turn it back on till just before you need it. If you're a typical city commuter this can increase your mileage by around 10%.

He makes the same caveats about starter wear.

See his full report on iwilltry.org.

[www.recumbents.com]

Hi All,

What speed do you pulse up to, and what speed to you glide down to during typical highway eco-driving? Is there an optimal speed differential between upper and lower limit?

Thanks,

-Warren.

[AndrewJ]

it varies. Ideally, you'd pulse up to the speed limit (or a little above) and glide all the way back down to a near stop. But few of us have the patience for that kind of thing, now do we?

I'd reccomend gliding down to the lowest speed that's comfortable for you, if you're on the highway though, most people try to keep a plus-or-minus 10mph thing going.
For example, pulse up to 55, glide down to 45. Rinse, lather, repeat.

[MetroMPG]

Depends on the vehicle also - my car doesn't P&G well at higher speeds because it's light and unaerodynamic (the glides don't last long enough to make it worthwhile).

What type of vehicle are you driving, Warren? Automatic or manual shift?

PS - welcome to the site.

[www.recumbents.com]

Originally Posted by MetroMPG

What type of vehicle are you driving, Warren? Automatic or manual shift?

PS - welcome to the site.

Thanks. It's automatic. A bone stock '98 gas guzzler maxima SE. The other half doesn't want me to destroy the resale value by making the aero mods I was considering.

I'll have to see how long it will glide from 65...

-Warren.

[MetroMPG]

Oh! That's your web site! I've looked at it several times before.

Before you start experimenting with P&G with your Maxima, do you have onboard fuel efficiency instrumentation? A ScanGauge?

[newtonsfirstlaw]

One thing I've noticed with P&G is that it confuses the people behind you. I will P&G if there is no one behind me, or someone following at a distance. With tailgaters I just go the speed at which I would end the glide. This tells them that I won't be going any faster and that they had better pass me if they want to go faster, rather than teasing them and getting them mad. It also saves me more fuel.

For people who tailgate hard, or flash lights or beep horn (happens once in a blue moon), I will slow down some more. I mean, what are they going to do, bump me? Attempts to intimidate might work if I was riding a motorcycle, but not in a car. If I am going a legal speed, they should learn how to change lanes.

[JacobAziza]

Originally Posted by MetroMPG
When you get good at clutch starting, it's very smooth. I recently showed the technique to someone, and I had to say out loud when I was killing the motor & when I had clutch started it.

I was teaching some hypermiling techniques to a friend recently.
She didn't realize that in order to coast you have to either hold the clutch in or shift to neutral, and consequently, she didn't notice the engine reengaging - and she was the one driving! I pointed out the tach reading, and explained the idea of bump starting.

I find in my (2.5 ton commercial) truck I can get the engine going easily at any speed above 5mph and barley feel it.
You get smoother with practice. I was kind of hard on the drive train the first month or so, but now I really not worried about wearing anything out.