Prius Prime Plus in my hands

The trick is the standard defines how to run the tests on a smooth, flat, concrete or asphalt road. It also specifies the speed range, temperature, and acceptable wind conditions. It is not that hard of a problem. Thanks to @bhtooefr, I was able to find the SAE standard although I've not bought my copy, yet.

Bob Wilson

 

As a quick hack, I took the 2017 metrics and selected all hybrids and unique test cars. Then calculating the HP @65 mph, generated this chart using the 'Target' coefficients:

I need to re-read the difference between 'set' and 'target' coefficients. Regardless, this gives a ranking of the power needed at 65 mph. Apparently the Accord had two different test vehicles with identical power required. The same is true with the Volt.

Bob Wilson

 

I was surprised to not see the "Prius c" in the 2017 data but that is not unusual as models that have not changed are omitted. Yet there was a Prius v. Look at #55 and pull down a copy of the raw data from the EPA web site.

Bob Wilson

 

My first daily commute in the new car:

• warm-up for MPG - still appears to take ~3 miles in 55F weather. I will have to do more tests but that was my impression.
• 28 mph minimum cruise control speed w/o radar target - happily there is no evidence of the drop-out seen in the Gen-3 Prius.
• dynamic cruise control - works great but when the school bus turned into a neighborhood, the cruise control dropped out instead of resuming to the set speed.
• Holy Carp is it efficient - seriously without plugging in, this car is awesome and much better than our Gen-3 Prius.

Now I will revert to our BMW i3-REx for my daily driver but this car appears to be a peer. It means if the BMW takes an extended stay at 'the spa', there will be little or no hit on driving costs. Better still, my hard requirement of reaching Nashville:

	model	speed	MPG
1	BMW i3-REx	65 mph	40 MPG
2	BMW i3-REx	70 mph	38 MPG
3	BMW i3-REx	75 mph	32-34 MPG with 20% SOC loss per tank; the 5th tank becomes speed limited to 65-70 mph or even lower
4	Prius Prime Plus	70-75 mph	~55 MPG with a stable SOC

The BMW i3-REx can reach Nashville or pretty much any distance needed with ~80 mile segments at ~40 MPG @65-70 mph. In contrast, the Prius Prime will reach Nashville at a faster speed and better MPG. Although I appreciate the EV capability, recharging on a cross-country trip stretches the block-to-block time to unreasonable values. You really have to treat cross-country as a gas engine performance metric to keep the trip time reasonable.

Bob Wilson

 

Just ran 10.8 miles on a loop at 28 mph, the slowest the cruise control would hold: 105.5 MPG. Temperature 61F (not quite standard range.)

Bob Wilson

 

I need to do a few warm-up tests but it looks like:

• 105.5 MPG * 11.4 gal ~= 1,202 miles / tank @28 mph
• 1,202 / 28 mph ~= 42 hours
• 2,789 miles ~= City Hall, New York City, NY to City Hall, Los Angeles, CA

Hummmmmm, I have an idea.

Bob Wilson

 

The tallest, local hill is 525 ft with an 8% grade. Certainly worth experimental verification.

Bob Wilson

 

So Tuesday morning I began mapping a new commuting route:

I call this file, 'prime_1k_010.jpg':

• mostly posted 25 mph in neighborhoods
• limited, four-lane, under used routes
• all very compatible with 28 mph cruise control

Bob Wilson

 

• 10.5 miles @28 mph -> 105.5 MPG
• 1200 miles @65 mph -> 55.7 MPG

Close enough,
Bob Wilson