ekpolk and others — I have in the past discussed at length the issue of how to use the instantaneous mpg (or L/100 km) displays to optimize trip fuel consumption (I forget offhand the name of the thread, but you may want to consult it). Effectively, the best I am able to say is that one should minimize the distance (not the time) spent travelling at poor instantaneous-mpg readings. There is, however, an interesting question that you may, using your new SG, be able to answer for me.

In the Canadian (metric) TCH, the FC gauge goes from 0 L/100 km at the bottom to 30 L/100 km at the top, with major tick marks at 10 and 20 L/100 km. The US FE gauge looks identical except the scale is labelled 60 mpg at the bottom and 0 mpg at the top, with major tick marks at 20 and 40 mpg. This cannot (or at least ought not to be!) just a simple relabelling of the metric scale, because the mpg scale is highly nonlinear. Toyota ought to have changed the FE gauge driving circuitry to correct for this nonlinearity. Have they done so? You could check this out for us.

If you set your SG to read in liters and kilometers, it will then display fuel consumption in L/100 km (LHK). What I would like to know is the SG readings (in L/100 km) corresponding to the following FE gauge readings: 10, 20, 30, 40, and 50 mpg. (Allow the car's FE gauge to stabilize before taking readings. This will take a few seconds, since the FE gauge averages over a 10-second interval, according to the Manual.)

The formula relating mpg to L/100 km is
L/100 km = 235.2 / mpg
and from this one can compute what the SG readings ought to be if the FE gauge's readings are indeed accurate. Let us know what your SG readings give.

Stan

 

I think that the thread SPL is refering to was titled something like ~ "An inconvenient truth, with appologies to Al Gore."

I don't think that the US version averages FE over ten seconds. I was able to turn the engine on and off this morning (cold ambient and engine) by just turning A/C auto mode on and off (even with ECO mode on). My point is, I saw the guage follow the engine run/not_run status directly (okay, maybe half second lag, but not 10 seconds!). Maybe I am misunderstanding your point.

I wondered about the same thing, optimal acceleration rate for good FE, when I first got my TCH. The only time I ever came accross a point I could use in a thread here was one user mentioned accelerating moderately. The hint he gave was to use 10 MPG on the consumption guage, until you get up to the desired speed (maybe he said go one or two MPH over, then settle back in). I tend to use this as a guideline. I try not to slow down other traffic, even when I am in the slow lane, which is most of the time. I also use the cruise control in the city a lot, to keep from speeding, etc. I know this is not the most fuel efficient mode.

Having said that, I should say that I do not get the stellar milage that some folks here report, even being here in sunny northern california (but I do use the A/C in summer). My lifetime MPG is calculated at 35.8 MPG, over about 20k miles. You may also be interested to know that according to my spreadsheet, my TCH has saved me $913 in gas versus a 4 cylinder camry. And the tank MPG reported is, on average, 1.2 MPG high (versus the calculated tank MPG).

 

I'm not going to be technical or anything, but along the same lines of standard acceleration, I was wondering if anyone had tips on going up hills. I live in a very hilly area, from where my house is to the bottom of the hill (only about half a mile, next time I'll get the exact distance) it's over a 700 foot decrease in elevation.

Is it more prudent, FE-wise, to gradually accelerate up to the speed limit from the bottom of the hill (after having lost a bit of speed and momentum), or try to be at the speed-limit and then maintain it once you reach the hill? That made sense in my mind, but I don't know if it translated to words, haha

 

Haroldo was a bit over the top in his own way! If I cut-out one Starbucks a week, I will just have to give it up Starbucks completely!!! Starbucks is our Saturday morning weekend planning meeting!!

Bring on the savings!! Can you relate your information in terms to those of us without the gadgets IE 0 - 40 in 9 seconds?

I have one more point that is important to this discussion. If WE find ways to improve efficiencies with our TCH that can be share with 5000 people reading this. We go a long way towards my personal goal of using less foreign oil. It's not just "Cut your average shower time by 4 minutes... Watch 11 minutes less television per day or Stop shaving.
SO keep the good stuff coming!! Bill

 

Referring to my post #21, the thread that I was referring to is "Acceleration question?".

Stan

 

chris_h — I have been unable to locate where I saw the averaging time of the FC/FE gauge mentioned. As I recall it said that the displayed reading was a running average of the past 10 seconds of data. Maybe I am mis-remembering, and it was 5 seconds. It certainly is not the instantaneous value in L/100 km or mpg — it is smoothed by averaging with a certain time constant. This does not mean that the gauge's reading is delayed by this amount of time, but rather that its rise or fall is "slugged" so that it takes a number of seconds to reach its final value. This prevents the needle from oscillating continually, and makes it easier to read an average value.

Stan

 

Okay, that makes more sense now that I undersand it better.

 

When I am driving in a "steady state" on level road, and then change the throttle position, the FE gauge reacts almost immediately and stabilizes at a new value within one or two seconds. This tells me that any "smoothing" algorithm, such as a running average of samples, must be over a time period of at most one second. This is rapid enough to be useful for acceleration control.

Using the FE gauge, over a period of several tanks, I have found a few things:
1. When I start from a stop, if the ICE runs, the FE dips below 10 almost no matter how gently I apply the throttle. I think this is because the distance per unit time is so small that even a small amount of fuel makes poor FE.
2. As the speed increases, the FE gauge recovers. Accelerating through 15-30 mph at 15 MPG is not difficult, though sometimes there is an impatient driver behind me.
3. Above about 30, I have to add throttle to keep the FE gauge down to only 15 mpg. If I hold steady throttle, at the position that got me 15 MPG in the 15-30 mph range, the FE gauge drifts up. I think this is because there are longer distances involved for roughly the same fuel flow.

Over several tanks, I tried to accelerate at 10 MPG. That experiment resulted in several 33-34 MPG tanks. Recently, I have tried accelerating at 15 MPG, up to about 30 or 35, and then constant-throttle (with higher MPG readings) up to speed-limit. That experiment seems to be yielding 36-37 MPG tanks. (Note that this is in heavy city traffic, with a highway commute, and mostly during rush hour, so I don't feel guilty about those MPG numbers.) (And, because of the city traffic and variable traffic conditions this is not a proper, controlled experiment.)

I conclude, based on this anecdotal evidence, that accelerating with the FE gauge at 15 MPG yields better FE than accelerating with the FE gauge at 10 MPG, by about 3 MPG on average. That is close to 10 percent improvement.

 

this was the best post you ever did. I couldnt stop smiling.

 

I live in Hawaii and for the first few months of owning my TCH I tried everything to make it not look like everyone else I put 20" rims blah, blah, blah... got into the fun of seeing how many miles i could get off one tank (most I got before the fuel light went on was 625) blah one day as I was driving trying to optimize my mileage. you know coasting slow long stops and starts etc. A man in another car (he was about 80) passed me and yelled "learn how to drive" I looked in my mirror and discovered I was adding to the already stoopid traffic situation in Hawaii, and at that moment decided to drive like a normal person once again. I now get 34 mpg a gallon and once again love my TCH and the rest of the drivers on the road dont want to kick my ***!