P&G acceleration rate and top speed advice

[theholycow]

You don't have to do math, just look at your tachometer the next time you're in that gear at that speed and you'll know.

As for [near] WOT and slow/quick acceleration...[near] WOT doesn't mean you're accelerating hard, it just means that your throttle is open. Sure, WOT in 1st gear will always be aggressive acceleration, but in 5th gear it won't.

However, accelerating fast can be effective in some cases, too. This is probably more true with automatics, since an unlocked torque converter is a machine designed to waste and it behooves you to get into high gear and lock the converter ASAP.

I've found that there are many conflicting strategies for saving fuel. They all depend on you understanding how and why your car works, how and why fuel works, etc. Once you understand that, whichever strategies you try are up to you, and you'll find which one works best for you but they'll all probably work better than not understanding.

For people who don't understand this stuff, the list of effective strategies is much shorter. Drive slower, drive more gently, keep the car in perfect stock condition.

[GasSavers_maximilian]

Originally Posted by theholycow

You don't have to do math,

Clearly, you don't know me very well.

Sounds like systematic testing may well be worth the effort to get some definitive answers. I learned a lot when I did it for level travel speed and fluctuation from car to car is apparently a lot greater than I thought. Answer more basic questions than P&G technique as well like "what's the best throttle for accelerating?". When I put it that way, I'm kind of surprised I haven't done it already. Guess my SG2 is paying for itself after all.

Sure glad I gave up on that ill conceived mpg simulator project.

[theholycow]

More on different strategies having the same results: In the second post in this thread, gary recommends limiting your throttle and pulsing downhill. I go WOT and do all my accelerating uphill, coasting downhill. Despite our opposite strategies, we get almost the same results - about 50% above EPA.

[GasSavers_maximilian]

Don't be so modest! You're getting 62% above! I'm at 50% or so now and am trying to break the 46 mpg barrier. Also, since my technique lately has been to use backroads to go very slow, I'm hoping for a higher average travel speed option. Having trouble finding a consistently better strategy in a lot of scenarios, which fits in with what you're saying.

[R.I.D.E.]

EPA combined on the Echo is currently 32 MPG. The old combined rating was 37MPG. Nothing here but 10% ethanol.

Last three tanks (need to add it to the garage) was 53 MPG for 1650 miles.

Average speeds for me locally are about 35-38 MPH. My normal route requires me to maintain 45 MPH to stay in the areas with timed lights.

My best 20 miles local trip was 82.7 MPG in the Honda Insight. Best highway trip was 70.2 MPG in the Insight, which is an automatic.

The Echo is a manual.

No hills here of any greater elevation change than a typical Interstate overpass, so you must consider that when you are talking about hills. My 70.2MPG trip in the Insight was elevation changes of close to 2500 feet.

I don't have a scan gauge to use in the Echo, no tach, not even a temp gauge. The Echo is very light at 2020 pounds and accelerates well in 5th gear from 30 MPH. I pulse from 40-45 to 55-60 on the 55 speed limit road, and from 35-40 to 50 on the 45 speed limit roads. On the 40 speed limit roads I pulse to 45 and coast to 35 MPH, sometimes lower.

I always try to pulse uphill and glide downhill, but that is due to the fact that the hills here are not much of a hill at all. The first 4.5 miles of road out of my neighborhood (going east) has no traffic lights and runs parallel to the railroad tracks. There are virtually no entrances or exits to cause problems with cars entering the highway. Elevation changes are obvious due to the railraod tracks being almost perfectly level. In fact for the first 7.5 miles of my trip there is only one light and almost no intersecting roads or entrances or exits of any type due to the railroad tracks running parallel. Its almost a perfect road to get mileage, 4 lanes (not divided) without much traffic as long as the parallel Interstate (opposite side of the RR tracks) is not plugged up by an accident.

I pulse uphill on long very shallow grades, and generally my pulse to glide ratio is in the range of 2 to 4 to 1. Sometimes it is much longer because I strategically use the slight downhill grades to extend my glides.

I also change my strategy when there are other cars on the same route that would be aggravated by my P&G strategy.

Sometimes I just go with the flow of traffic and go between 45 and 55 MPH. Rarely I will just get on the Interstate and grab a 3 stripe draft, which gets me almost the same mileage as 55 MPH without any draft.

regards
gary

[FrugalFloyd]

Originally Posted by maximilian

Something that's bothering me; how is all this accelerating near WOT talk reconciled with other advice I've seen that suggests accelerating slowly? I never accelerate fast under any circumstances other than coasting right now. Have I been mistaken in my interpretation of the advice?

Google Brake Specific Fuel Consumption or BSFC. It explains why moderately aggressive acceleration is better than slow acceleration for getting the most work done/unit of fuel.

[GasSavers_maximilian]

Just gave rev matching a shot and it's incredibly easy. Awesome.

[theholycow]

It should make your driving smoother and allow you to release the clutch pedal faster, too.

[GasSavers_maximilian]

Did my first grocery store run with P&G used consistently and my SG2 recorded 52.0 mpg for the round trip (vs a little over 45). I found ways to P&G even with light traffic and in slow speed zones. By adjusting throttle, min and max speeds, and knowing the routes really well it was surprisingly easy to adapt. I even use P&G when backing out my driveway now! Before I'd use a steady throttle the whole way. hehe

[theholycow]

One of the nice things about P&G is that you can integrate it with normal traffic/road needs by just predicting what's coming up, and adjusting your P&G schedule to match the conditions.