Tested: The Most Efficient Way To Accelerate With An Automatic (Toyota Matrix)
 

The most efficient speed to cruise at with an automatic transmission (at least the kind with a torque converter) is the minimum speed that the torque converter will lock up in high gear. For my wife's Toyota 2007 Matrix (1.8L, four speed auto), this speed is 60 km/h (37 mph). The most efficient way to accelerate above this speed is at max load without the torque converter unlocking. For the Matrix, this is 75% "LOD" on the ScanGauge II.

The question that has plagued me for a while is, what is the most efficient way to accelerate up to 60 km/h? Slowly? Quickly? Today I finally got around to executing a test using my SGII.

I first determined a fixed distance to test with by accelerating very slowly from a stop to 60 km/h. As soon as 60 km/h was reached, this was the fixed ending point, using signs and trees beside the road as markers. This distance ended up being 740m (2400ft), going by Google Earth.

For every [quicker] run after that, 60 km/h was reached before the ending point, so the remaining distance was travelled with the torque converter locked at a steady 60 km/h, with the final L/100km figure taken at the fixed ending point.

The two constants were the test distance and 60 km/h vehicle speed at the ending point.
The variable was the acceleration rate up to 60 km/h.

What I found was quite surprising. Different acceleration rates have little effect on efficiency with this car, from ulta-slow to very fast. And the most efficient acceleration rate is much quicker than I ever thought it would be.

Test results chart:
http://i1119.photobucket.com/albums/...psff2047ff.png

Test results graph:
http://i1119.photobucket.com/albums/...ps569a3e5c.png

I've been wondering the same thing for my '01 Corolla. I imagine my results would be pretty comparable. Thanks for testing and sharing! I think I'll stick with my 'ultra slow' to 'slow' range of accelration for now. :D

Did you do multiple runs for each pace? I would imagine 3-5 times for each one would be at least the minimum to have a more concrete experiment/results.

My only concern is that (it appears) you only did one run. From first to last you have the variable of engine temperature, which traditionally gets hotter more efficient as it goes up. One run also does not account for a wind change, temporary draft, so on.

So, to account for this, immediately after very fast, ultra slow would have to be redone, if one wanted to better delete the variable.

Don't get me wrong, I only do one test run (after I warm the engine) of all my speeds for my own personal record keeping (it's too expensive to test well!), I just wanted to bring up this point.

Nice testing! :thumbup: Yeah, could use more runs, but it gives you a rough idea of what Darin and I have said for quite a while. Acceleration method doesn't play a huge role in fuel economy. I prefer to accelerate briskly (hey, if I can, why not? :)), while he tends to prefer to accelerate more slowly, but we can and have both achieved over 100% above EPA with our cars.

Its what you do after the acceleration that matters (dont brake!)

I also think its hilarious to tell people that its efficient to floor it. :)

I should have elaborated. I did the test after running a whole bunch of errands, so everything was nice and toasty warm, up to operating temp.

I did the first run three times in order to get a concrete fixed distance (it was hard to concentrate on driving and watching my markers so I wanted to be sure) with the same result each time. All other runs were single runs.

I think a good rule of thumb for autos is as fast as you can without delaying the upshift.
I think of it this way, highest load combined with the least possible actual revolutions of the crankshaft to get to your target speed. In lower overall geared vehicles that will be pretty quick. Taller geared will be slower, but it really makes little difference, so I like to move with the flow of traffic and be stealthy while getting great mileage in all my vehicles.

Now the bike is a different game for me. It's fun to just get it on down the road and I can do that on the bikes and still beat 60 MPG. I confess I was trying some coasting on the 94GS today, it might get me another 10% if I can maintain the effort, but I don't like to create distractions when riding on two wheels. It's kind of a passive agressive technique which maintains best separation from the inattentive and imbecilic, especially now that deer season is here.

regards
Mech

My first thought was "How far was this from your starting point?" Someone posted on here today that it took his car three miles to warm up. That seems reasonable, but in the Phoenix area, our engines should not get too cold.

I think that I accelerate faster than most, but I do not stomp on it. I was surprised that you accelerate to 60 KPH in 740m. According to Google Maps, an on-ramp is 400 m, and I hit 55 MPH (88 KPH) in that distance.

By my math, it takes me 32-33 seconds to reach cruising speed. I accelerate as hard as I can without the transmission downshifting.

UltArc, how quickly do you accelerate? :)

What does it say that I am asking the guy with a Mustang? :)

I had been accelerating slowly, but when I bought my Ultragauge and saw the prolonged single-digit MPG, and then when I accelerated faster, I saw higher numbers, allowing me to stop accelerating sooner, it seemed overly simple.

Believe me, 60 km/h in 740m is very slow. Painfully slow. Like old man with a beard driving a Volvo slow. I am very happy that my findings revealed that slow acceleration doesn't really help economy...it's all about what you do afterwards.

There were a few times when, before I had my bike back, I would drive to the grocery store half a mile away or one of the nearby Mexican restaurants. Thinking that I would get astronomical mileage by driving without accelerating, since it was night and the street was empty, I would just idle the entire way there. It would have been faster to ride my bike and properly secure it once there!

I forget what my mileage was, but I drove the speed limit, or a little higher, as soon as I saw the number.

Cool info, Thanks given.
I always thought maybe, the quicker you get up to speed, the sooner you can get out of the throttle.

How about stick shifts? Same idea float?