100+ hypermiling / ecodriving tips & tactics

[ttoyoda]

cloudjunkie,
darnit, you beat me to it on the perpetual motion post.. I was sooo looking forward to typing that in.

A few nits about your calculations, though. 1 HP is 746 watts, so 10 HP is 7.46 KW not 7.6.
AFAIK 100 watt bulbs are off road, not DOT, not that I mind
Now lets look at losses in the alternator, which I think are significant.
200 W at (assume)12 V = 16.67 amps. Assume the diodes in the alt. have a .7 volt forward voltage drop. We waste 16.67 * .7 = 11.7 watts just in the diodes. Then there are other losses that I cannot really estimate: losses in the windings, both the rotor and the stator. Voltage regulator losses. There are belt flexing losses driving the alt. plus the possibility of a tiny bit of belt slip or creep. Bearing losses. Possible increase of friction in the crank pully engine bearing due to the greater tension of the tight side of the belt, although you could also argue it makes no difference. Then there is reduced lifetime of the alternator, which has some cost as well.

[MetroMPG]

Originally Posted by Tango Charlie

Great list!
How about this one;
Imagine an egg between the accelerator and your (bare) foot. Helps prevent jackrabbit starts.

It's worth posting. You'll notice the list has a big omission: there's no discussion at all about ideal acceleration rates. Mostly because it's one of those big "it depends" (TM) situations. EG: auto vs. manual transmission; what are you going to do after accelerating (cruise? glide?)

It's probably true to say that jackrabbit starts are wasteful, but some people might take that to mean that glacial acceleration is the most efficient. Which also isn't true for all vehicles/situations.

And maybe I missed this one on the list, but;
Never Downshift

In general, yes, better to coast! But sometimes downshifting can save fuel: If you've come into a situation where you need to slow down (can't coast), you can use DFCO (deceleration fuel cut off) if your RPM is high enough. Save a few drops rather than braking while idling.

[dcb]

Probably better to imagine an egg between the brake pedal and your (bare) foot

[LostCause]

This idea is kind of out there.

Power brakes take energy to use, right? When stopped on an incline, I let the automatic transmission arrest my rearward motion. Those fortunate enough to have manual brakes don't have this issue.

I imagine the universal solution is the emergency brake. I've though about using it on hills that are too steep and when stopped on flat ground to keep the car from creeping forward. Just an idea...I have no idea if it works.

- LostCause

[MetroMPG]

Originally Posted by LostCause

This idea is kind of out there.

It wouldn't be the only "out there" idea on the list :P

And to arrest forward creep in an automatic, why not just shift to neutral?

[Tango Charlie]

Originally Posted by LostCause

This idea is kind of out there.
- LostCause

I get that sometimes...
Maybe the egg thing would fit under tip #93: 'Be Smooth"
Where would downshifting fit in the list under tip #43:'The most efficient way to slow down' ?

[LostCause]

Originally Posted by MetroMPG

And to arrest forward creep in an automatic, why not just shift to neutral?

That's a good point, will do.

I think I have some psychological hangup seeing the rpms rise in neutral.

Reading through the list, #61(?), the gravity parking assist, was pretty awesome. That's hypermiling at a whole other level.

- LostCause

[jamesqf]

Originally Posted by LostCause

Power brakes take energy to use, right?

Wrong! Well, technically it takes energy to use them, but such a trivial amount that using the transmission would probably use lots more. All the power brakes do is use a tiny fraction of the engine vacuum to amplify the pressure of your foot, so it might use 3 or 4 times the energy it takes to move your foot a few inches.

[LostCause]

I think my power booster provides ~250lbs of assistance, which is a decent amount of force. When my booster leaked, it would cause my engine to stumble at anything under 1000rpm. It was a nice little reminder: vacuum isn't free.

My brakes would be counteracting transmission creep on the hill anyways. It might only save 0.000001 gallons, but hey...that's 0.000001 gallons for free. I'll take it.

In any case, I started using the emergency brake method on moderately long lights instead.

- LostCause

[COMP]

Originally Posted by Frank Lee

The upside of that habit is your emergency brake won't freeze up on ya with regular use.