2010 Prius Preview: A Hypermiler's perspective

[Dan.]

Originally Posted by MSantos

Yet another great piece. Thank you.

Thanks!

Originally Posted by bwilson4web

I enjoyed the write-up especially because it included the average mph. Just a couple of quick technical questions:

1. temperature of each run?
2. ethanol or straight gas in area?
3. normal octane rating of regular gas in your area?

Google Earth shows Tuscon to be about 750m, a significant improvement over the 180m in Huntsville. Is there a way or a set of way-points you might share that shows the the route taken?

1. 88 degF
2. Don't know if they were filled before they arrived, or filled in Tucson.
3. They spec'd the Prius for Regular, not Premium, but I don't know what the exact octane rating was.

Originally Posted by usbseawolf2000

You may want to mention the Exhaust Heat Recovery system is not only to help the short trip but also a setup for the PHEV version. PHEV Prius will be able to shut down the gas engine much faster after the gas to come on to assist during hard accelerations.

Well I asked them point blank (Chris and Doug) if any of the features in the 2010 Prius were there to Pre-Enable PHEV. Answered categorically "NO!". May just mean they didn't want to go on record with it. The EHR really does keep things nice and toasty. As far as transitions from ICE-on to ICE-off, I didn't notice it cut out quicker, but it did cut out easier. In the 2009 Prius you have to come *WAY* off the throttle to cut the engine, on the 2010 prius there is no need "feathering" the throttle to coax an ICE-off event. Once your power demand is low enough its off. As soon as you demand more, it's on. No gray area to navigate through like the Gen II Prius.

As for the route, here it is... I'll google map it in a bit perhaps.

Start:
7000 North Resort Drive
Tucson, AZ, 85750

00.1mi - Turn Left on Kolb.
02.7mi - Turn Right onto Sunrise.
06.3mi - Turn Left on Campbell.
16.7mi - Take I-10 East towards El-Paso.
21.3mi - Take Valencia Exit.
21.6mi - Turn Left on Valencia.
24.6mi - Turn Left on Kolb.
32.3mi - Turn Right on Tanque Verde.
32.9mi - Turn Left on Sabino Canyon.
35.0mi - Take Kolb at fork.
38.4mi - Turn into Hotel.

Here's an elevation map of the route. Over 800ft drop from the high to the low!:


Here's the Google Map of the Route.

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[efusco]

Great review Dan, from a perspective perhaps few of us really appreciate, but greatly need. I'm not sure the MPG difference is significant beyond the proof in the pudding that you can approach and or exceed the '09 with minimal practice...letting us know that we should see some huge numbers in the first few months after the '10 hits the streets.

[bwilson4web]

Originally Posted by Dan.

. . .

1. 88 degF
2. Don't know if they were filled before they arrived, or filled in Tucson.
3. They spec'd the Prius for Regular, not Premium, but I don't know what the exact octane rating was.

Thanks! This helps a lot. I'll check with my brother but my understanding is higher elevations sometimes have 85 octane fuel available.

Originally Posted by Dan.

. . .
As for the route, here it is... I'll google map it in a bit perhaps.

Start:
7000 North Resort Drive
Tucson, AZ, 85750

00.1mi - Turn Left on Kolb.
02.7mi - Turn Right onto Sunrise.
06.3mi - Turn Left on Campbell.
16.7mi - Take I-10 East towards El-Paso.
21.3mi - Take Valencia Exit.
21.6mi - Turn Left on Valencia.
24.6mi - Turn Left on Kolb.
32.3mi - Turn Right on Tanque Verde.
32.9mi - Turn Left on Sabino Canyon.
35.0mi - Take Kolb at fork.
38.4mi - Turn into Hotel.

Here's an elevation map of the route. Over 800ft drop from the high to the low!:


Here's the Google Map of the Route.

Perfect!

The cooled exhaust gas may have come into play on the final climb and this remains an area that I have a lot of curiosity.

Do you remember your speed on the final climb?

The reason I ask is some of my hill climb tests show there are optimum climb speeds on either side of a worst climb speed:


At speeds above 70 mph, the NHW11 Prius begins to draw significant power from the traction battery. This extra energy more than compensates for the engine inefficiency at high power settings. Of course the hill has to end before the battery is exhausted.

If the ZVW30 cooled exhaust keeps the brake specific fuel consumption in an optimum range even at full throttle, speeding up a 6% grade may be the best way to reach the top with the lowest apparent fuel consumption. The key is accelerating on a flat or descending area to the maximum, safe climb speed and then holding a constant speed when blasting up the hill. Speeding up a hill sounds counter intuitive but the data shows otherwise.

NOTE: 525 ft. hills are not that high. Worse, repeated cycles will 'charge heat' the traction batteries. This is really a 'one time' technique and not recommended for hill country.

Untested, one might be able to time backing off to let the vehicle momentum crest the hill at final cruise speed. This is a tricky proposition and requires a table to do it right. Still, it is an interesting, future experiment.

Bob Wilson

[Dan.]

Originally Posted by efusco

Great review Dan, from a perspective perhaps few of us really appreciate, but greatly need. I'm not sure the MPG difference is significant beyond the proof in the pudding that you can approach and or exceed the '09 with minimal practice...letting us know that we should see some huge numbers in the first few months after the '10 hits the streets.

Exactly. I think the Gen III is indeed a bit more efficient than the the Gen II. A hypermiler will drive both to their full potential. The reason I think the Gen III scored so much higher on the EPA FE rating is that the new firmware is a lot smarter and allows an inexperienced driver to do a lot better than they would on the Gen II. These new smarts seem to show up in the fact that the engine is much more willing to shut off if you lighten your throttle, and the ECO-Mode has a definite smoothing effect on throttle. This threw me for a bit, but once things clicked, everything starting falling into place.

The beauty of the EHR combined with the forgiving firmware, combined with the 4 drive modes means that fewer people should find themselves way off the bell curve as far as MPG goes. If your MPG is low, just do a bit more granny driving and put it in ECO mode instead of PWR mode. They even have an "ECO" indicator that drivers can use to train themselves in proper acceleration.

Originally Posted by bwilson4web

Do you remember your speed on the final climb?

My final climb was running at about 1600-1700 rpm, steadily accelerating from 45kph up to about 57kph, then I'd come off the throttle till the engine cut off and decelerate back down to 35-45kph. I'd try to time the "glides" (decelerations) around flats in the terrain.

Back to the OP, one thing I didn't mention is the fact that at the bottom of the first big hill was a light. Caught it red on both runs. So almost none of the speed on that decent was used in the rest of the course. I did get a good charge on the pack though.

[HTMLSpinnr]

I believe Tucson may have ethanol gas like Phoenix metro. Don't think we see 85 octane here though - only in Colorado.