Best way to accelerate

I find it is best to accelerate somewhat rapidly from a stop sign or stop light. Once I reach about 28 mph, I engage the cruise control, then use the cruise control to accelerate further. This seems to be a good balance between the ICE and electric modes. Police pursuit driving trains you to have a sense of your "seat" and the center of balance in the vehicle. Coupled with the sound of the engine, you quickly learn how fast to effectively accelerate. Braking shifts the center of gravity to the front wheels, acceleration shifts the center of gravity to the rear wheels.

As conditions permit (light traffic, not major highways) I can set the cruise control at 41 to 51 mph (depending on road grade) for optimum continuous performance (velocity, fuel economy, battery recharge). I have been concerned about fuel consumption, but average 51-53 mpg using this technique.

On major highways I continue to accelerate with the cruise control to 66 to 70 mpg and average 45-51 mpg with continuous driving.

 

I believe that a slow steady acceleration is best.

If cruising speed is over 40, I try to accelerate using only the ICE, not drawing from the battery. (Keep the arrows to the battery or no arrows to or from the battery). Accelerating faster drains the battery which then requires recharge and consumes energy. If cruising speed is under 40 , I try to stay in EV as long as possible and then feather into EV as soon as I can. This of course depends on how close I'm being tailgated!!

I believe in Physics and the laws of conservation of momentum, and efficiency. It takes a certain minimum amount of energy to accelerate a mass to a certain speed. The time it takes does not matter, however, doing it too fast requires extra energy and is less efficient. Doing it slower may help if you can stay in EV. It is not a matter of getting up to speed in ICE as fast as possible to get to EV sooner. Watch your MPG when going at different acceleration rates. Pedal down and MPG is 6 to 8 or so. You use a lot of extra gas to overcome inefficiency (but it is fun when you can stop that punk in the right lane from getting in front of you just because he thinks he's got a fast car).

Remember, the idea is to use less gas. The less gas you use, the better the MPG will be. As you drive think: how can I drive with less gas usage? Can I coast a little more? If I let off a liitle up this hill, I can get back up to speed on the down side. Nobody behind me - I'm coasting a 1/4 mile to the stop sign. If the speed limit is 40-45, I'm doing 39 to be in EV (as long as nobody's behind me).

Anything over 63-65 really starts sucking down the gas - wind resistance. Over 70-75, you might as well be driving anything else on the road. I never use cruise control. I tried it, and I do much better. It can't anticipate, it can only react.

 

Brisk acceleration (but not hard acceleration) is better. If I don't have anyone behind me, and can accelerate in electric mode, I will until the ICE kicks in and then I accelerate briskly up to the cruising speed. If there was a direct conversion of the gasoline into kinetic energy, then I would agree that the rate of acceleration did not matter. Unfortunately, internal combustion engines are not that straight forward. Watch the instantaneous MPG reading and try a slow acceleration, and then a brisk acceleration. I think you'll find that accelerating twice as fast won't mean that you use twice as much gas. However, try a hard acceleration, and you'll find that gas consumption goes way up.

 

I am presently in the brisk acceleration group. I am very interested in the course of this thread. I really picked up on this on a weekend when I had to make a few banzai runs to the hospital. I thought I was really going to take a hit on the M.P.G. but I actually did a bit better that expected. I am of an age where I am beyond drag race starts and speeding, but I do need to move along. I would like to hear more from the most experienced folks around here.

 

Ok, I'm really curious as to which type of acceleration is better. Please post some MPG figures as well as miles on the odometer to compare which saves more gas. Certainly different factors will influence the MPG of each person but maybe we can see a general trend.

 

I am certainly not one of the most experienced at this yet, but I started with mild accelerations and have been experimenting with more brisk accelerations. I have not determined yet the optimal level of "briskness" quite yet, but I do believe it is more efficient on the whole than the slow starts.

My $0.02,
Powers.

 

i use the motor as long as i can then when the engine turns up do a brisk acceleration then just cruise at the speed i want. I think getting kinda bad mpg for like 3-4 seconds is better then getting decent bad mpg for a much longer period of time. Kinda like lifting a really heavy weight you use less energy just getting it up fast (up to a point) and letting momentum help you rather then lifting it slowly.

 

start off in electric till about 20Km per hour, 12 miles per hour, that usually starts the ICE and then do 3500 RPM till I get to almost the speed limit and then completely back off the trottle which makes the computer think your going to coast then slowly add throttle to maintain speed. I don't pulse drive. Most times I'm better than the cruise control as we have lots of hill here, unless I'm on the hiway then it's cc all the time.

 

ive attempted several times to drive any appreciable distance using both gradual and brisk acceleration and have never been able to stick to one or the other for a long enough period of time to get any real difference in data.

unless you can do this in a controlled environment, its nearly impossible to pull data out of driving when all driving conditions affect your mileage so much.

brisk or gradual acceleration can be a minimal or significant factor in the overall gas mileage you get. i have often kicked around the idea of going to a large parking lot where i can get up to say 40 mph. i figured something at least a half mile in length where i would either accelerate and drive before coasting a block or so while coming to a stop, turning around and doing it again several times.

then try accelerating very gradually up to 40 mph and slowing down at the same rate as before.

but just havent been motivated enough to try it.

to be honest with ya, i think the slower you accelerate the better the mileage just like any other car. i understand that the slower you accelerate the longer the ICE runs. but in the grand scheme of things, it still takes the same amount of force to go the same distance. so we have to look at what is more efficient. batteries are notorious for being inefficient and converting energy to electricity isnt that efficient either. now after the electricity is made, electric motors are very efficient but its still all coming from gas so i feel that using the electric motor is efficient but using battery power isnt.

so we come to gas engines which are notoriously bad for wasting energy. but when the Prius is running the engine to power the AC motor, that is where its at its most efficient. The ICE by its design is meant to maintain momentum not accelerate. so i believe that fast acceleration is using the Prius at its worst. when you have primarily the ICE working especailly for high torque applications you are losing because that is what the EV was for.

 

My opinion: Just drive it!

Interestingly, the original poster asked what is "best" without specifying any criteria. If you could increase your mpg but get intentionally rammed, or even shot, by some lunatic in a fit of road rage because you took 5 seconds longer to get up to speed than the cars in the next lane over, that is clearly not the "best" outcome.

But I agree with Evan, above (and with John1701a) that you get the best performance with a brisk (not jack-rabbit) acceleration.

While it's true that batteries are not efficient, simplistic analyses will not work with such a complex system as the HSD. Accelerating on battery power alone is probably a bad idea because of the battery inefficiency, the relatively small amount of energy stored in the battery, and the large amount of energy required to accelerate the car. But trying to force a dead-band (no battery) acceleration is probably not a good idea either because it is not taking advantage of the whole system. The Prius is designed to use gas and electric together, and is probably at its most efficient when allowed to do so.

 

With the Classic Prius, I swear by the slow start. However, the 05, I'm leaning toward a more brisk start. My wife has had the 05 Prius the last couple of days. She runs the heater, I don't. She drives more quickly than I do including the acceleration and abrupt stops. Somehow she added 2 to the mpg when I suspected she'd lower it by 2. This is with over 200 miles already on the tank. I just don't get it.

 

I've done a lot of experimenting with the advantage of extra instrumentation. Read Evan's comments carefully - I think he's nailed it, and there's no need for redundancy (just a geek's endorsement).

 

I keep up with traffic, period. I don't go faster, and I sure don't go slower. In city traffic, or busy intercity traffic, keep up with the flow, period.

A lot of Americans have watched Michael Moore's "Bowling For Columbine" and have the wistful notion that Canada has zero crime and we all leave our doors unlocked.

Two words: Bull and S***!

Home invasion is one of the fastest growing crimes up here in the Great White North. Leave the doors unlocked? Wow, what is that Michael Moore smoking?? ukeright:

Road rage can and does happen here, and even guns can be involved. More often though, you can be rammed off the road, or the person will force you to stop and then stab you or beat the s*** out of you.

Then thanks to the Liberal Left Wing judges, the crook only spends 2-3 months in jail. If he goes to jail. There was even a case here in Winnipeg around 5 years ago when two off-duty RCMP officers committed an act of road rage. They got off.

As far as finding the "optimal" acceleration band, that would be easier if the Prius had a tach. The Insight does, why doesn't the Prius??

 

Well that's it... I'm not moving now.

 

A tachometer would be pointless in a Prius, because the engine speed is almost completely decoupled from the vehicle speed. The PSD allows the engine to run at or near its most efficient speed regardless of vehicle speed.

 

I think Jayman is just trying to discourage us US-ers from moving to Canada and ruining a good thing. I've been to Winnipeg (several times), Regina, Saskatoon, and the Selkirk Mountains of BC, and I think Canada is a great place with great people. Sure, there's crime everywhere, but if I didn't have roots here in Fargo, I'd be sorely tempted to move to Canada. Jayman, you've got a great country!