How hard to you push from 0 to 60

Assuming traffic isn't holding me up, I usually accelerate with the pedal somewhere around 3/4 of the way down.

 

I usually floor it, regardless of if there's someone behind me or not. I like to get up to cruising speed quickly and stay there, FE be darned temporarily.

 

<div class='quotetop'>QUOTE(Rancid13 @ Sep 15 2006, 04:17 PM) [snapback]320284[/snapback]</div>

that's me too. those times when i'm merging or passing, i rev it up and go.

 

If I am not holding up traffic I just go slow until the ice kicks in then I floor it to cruising speed. If traffic is an issue, I get up to cruising speed as fast as safety allows. Getting on the freeway I just put that pedal to the floor and go.

 

I normally accelerate at 2700 rpm till I get about 8km (5 miles) an hour below the speed limit then back off so that I get to the limit in a reasonable time provided there is no one with their nose up my butt. Most times this puts me ahead of the pack. More so when gas prices started to peak. Now I find that there is some moron who is trying to save money by slowly accelerating to the speed limit if they get there at all. I'd like to show them that they are wasting fuel instead of saving but most wouldn't understand an instant fuel consumption read out.

 

Gas engines are most economical at full throttle (i.e. power produced per amount of fuel used). If you are trying to get maximum efficiency, then floor it till you are at the speed you want.

 

I generally accelerate briskly up to my target speed so that I can start cruising as quickly as possible. The way I look at it any kind of acceleration clobbers the MPG so the sooner I can start cruising the longer (and more distance) I'll be moving as efficiently as possible. The only time I gently accelerate is when I'm running in EV mode or coming down a hill (it's also about the only time I really speed... when I can get the extra mph without burning even more gasoline/current).

<div class='quotetop'>QUOTE(DocVijay @ Sep 15 2006, 08:26 PM) [snapback]320352[/snapback]</div>

I thought they were most efficient at about 70% of their max output (for an otto cycle engine anyways).

 

The engine map for our engine included on slide 51 in a technically rich presentation linked by ken1784 indicates that the PriusII engine is most efficient around 2300 RPM. This actually shows the fuel used per unit of energy produced, as it varies with RPM and torque! Later slides in the presentation suggest that this most efficient output is around the energy required to maintain a flat cruising speeds of 70 and 80 mph. I don't have my ScanGaugeII yet, so I can't quantify this in terms of acceleration or other terms. Perhaps someone with a ScanGauge, tachometer, or CAN-view can?

This only considers the engine efficiency. The engine map suggests that our Atkinson cycle engine doesn't lose much efficiency at any moderate load or RPM. On the otherhand, there are great opportunities for energy losses from braking, mechanical-electrical-chemical energy conversion, and aerodynamics. Hypermilers know that as you accelerate, following three primary rules lowers fuel consumption:

1. Don't accelerate so hard that you draw energy from the engine and the battery simultaneously. Try to not accelerate so mildly that the car feeds a lot of energy into the battery.

2. Don't accelerate to brake. Conserve the kinetic energy when you have it. Don't invest in kinetic energy you'll have to brake away.

3. Remember that the greatest losses (energy and otherwise) come from car accidents. Avoiding these should always be the first priority.

After these concern's I'd generally recommend an RPM around 2100 - 2500 when accelerating.

 

<div class='quotetop'>QUOTE(DocVijay @ Sep 16 2006, 11:26 AM) [snapback]320352[/snapback]</div>

Wrong, wrong and wrong, count three.

1. As Tripp and theorist said, the most efficient position is a partial throttle.
2. Ours are "Drive-by-wire". We can't make it full throllte even flooring on 0-60 mph area.
3. Such flooring makes the HV battery discharges hard, which means you'll see worse fuel economy.

Ken@Japan

 

I never floor the pedal except if I want to measure 0-60 times to see if engine is working at proper power level.
I might sometimes get the accelerator half way down, but only to get proper stealth switching.

 

Agreed, full throttle on most gas engines changes the fuel maps dramatically. I know the PE (power enrichment maps) changes the AFR (air/fuel ratio) quite a bit and you run less effiently. IE, normal part throttle cruising AFR is usually around 14.5 but under WOT conditions AFR drops to 11.5 (forced induciton cars) or 12.8 (naturally aspirated). This extra dumping of fuel is not good for economy. If I floored my truck everywhere I go my milage would drop like a rock!

 

<div class='quotetop'>QUOTE(F8L @ Sep 16 2006, 11:45 AM) [snapback]320534[/snapback]</div>

Bingo. Pumping losses are less if the throttle's wide open. But during acceleration the mixture is richened significantly so mileage goes down.

For mileage purposes, I tend to accelerate as slowly as the traffic flow will bear.

 

<div class='quotetop'>QUOTE(Pinto Girl @ Oct 31 2006, 07:26 PM) [snapback]341623[/snapback]</div>

I thought the big idea behind pulse and glide is replacing long periods of light throttle with shorter periods of moderate throttle and periods of engine shutoff. This is the reasoning advanced by those at CleanMPG.com and the reason that hypermilers used pulse and glide long before the Prius. I believe that thermodynamic inefficieny at very light throttle is as much of an issue as the pumping losses of a nearly closed throttle.

Luckily the Prius will turn off the engine (or at least the fuel flow above 42mph) and rely on the battery when the acceleration demands are very small. So if the battery's state of charge (SOC) is good, you don't need to worry about the inefficiency of the engine under very light loads, at least not when it's greater than the inefficiency of the mechanical to electrical to chemical to electrical to mechanical energy conversions required to use the battery. That's why pulse and glide is still beneficial on the Prius. It's also much more convenient, safe, and legal than the non-hybrid manual implementation of pulse and glide with a manual transmission.

 

i'll step on it, but not stomp. i like to get up to speed pretty quickly.

 

I go up to just as much as I need to, to merge in, which ideally is around 50. Then I take advantage of the terrain or other conditions to gain speed up to 60. I rarely go faster than that, even when the limit is 75. At least so far.... I'm still pretty new to this! But I will go faster if the traffic around me is. Usually if I hang out in the right lane, 60's about right.

 

I guess I'm just old, 15,000 miles and I have never felt the floor.

 

I tend to accelerate hard enough so that no arrows goes to/from the battery. This seems to be around 60%-75% of full throttle.

Theorist seem to say that you should accelerate slow enough so that the battery can be recharged. This would be a lot slower acceleration and seem to be against some of the recomendations I've seen here.

 

<div class='quotetop'>QUOTE(SomervillePrius @ Nov 1 2006, 12:09 PM) [snapback]341906[/snapback]</div>

That should be close to the best strategy, or as close as an observant driver can easily get in practice. The engine will be somewhere near its most efficient RPMs, and it reduces energy conversion losses (which occur unavoidably whenever power flows into or out of the battery). The best use of the battery (*) is in recovering energy when you slow down, when the energy would otherwise just be thrown away as heat by the brakes.

(* The other best use of the battery is to floor it and dust a BMW, Charger, etc. at a stop light, to show them that hybrids are not chopped liver.)

 

<div class='quotetop'>QUOTE(SomervillePrius @ Nov 1 2006, 11:09 AM) [snapback]341906[/snapback]</div>

Actually, I am with you. The idea is that the battery is used to keep the engine load in the efficient zone. If acceleration demands are too low, the car will feed the battery; too high and the car will draw from the battery. Either avoids engine inefficiency but incurs battery losses.

I guess 'moderate' acceleration is not to precise. Another way of measuring this is that during pulses I like to use fuel at a rate of around 1.5 GPH (gallons per hour) while pulsing below 41mph. Without a ScanGaugeII to display GPH, this means that instantaneous MPG is less than MPH but more than half of MPH. To give you another sense of the throttle position, this is around the engine load or rather the GPH required to cruise at 75mph.

Pulsing and gliding in this way (and not allowing the battery to recharge during glides) will often bring the battery's SOC to 4 or 5 bars as a steady state. This is lower than the typical 6 bars that results from typical driving.