2017 Toyota Prius Prime: Price + Content + Efficiency = WOW!!!

Toyota needs to update the engine and battery on the rest of the Prius variants to the running gear in my Prius.

 

I rented a Prius Prime this past weekend for 24 hours. The reason I rented one is that I'm going to buy either a PHEV or a BEV this year, and I wanted to see what it was like to live with for 24 hours. Mostly what I was curious about was some of the real-world charging logistics at my apartment (I'm a renter, but there's a garage with electricity for tenants to use), but I was also curious about efficiency, ride quality, comfort, etc. too. The reason I rented a Prius Prime is not so much because this was at the top of my list, but because it's extremely difficult to rent any PHEVs or BEVs, and the Prius Prime was what was available.

My general impression: this is a fantastic car. The ride and handling were way better than I expected. The ride felt smooth and soft, and the steering felt more precise than my 2016 Civic LX (perhaps because the Prime was basically brand new). The leather seats were also very comfortable; my family has a 2008 Camry hybrid with leather seats, which I find to be uncomfortable/stiff - the Prime's leather seats have much more softness and cushion to them. The Prime also felt sturdier than the Ioniq PHEV that I test drove in March (though that test drive was only for 5 miles), and the rear visibility seemed better in the Prime too.

But what was most impressive was the efficiency. Long story short: over 118 miles, with temps in the 60s and 70s F, and driving on mostly 55 MPH highways, I consistently got 39 all-electric miles from a full battery charge and I consistently averaged 6.5 miles/kWh.

Short story long: I took 4 trips in the Prime.
The first trip: a 47.0-mile mostly highway (55 MPH speed limit) drive from the rental location back to my apartment.
The second trip: a 22.6-mile mostly highway (50 MPH speed limit) drive from my apartment to my job and back.
The third trip: a short, 4.0-mile city drive (25-30 MPH) just to show my wife how quiet the Prime was (she wasn't that impressed).
The fourth trip: a 44.7-mile mostly highway (55 MPH speed limit) drive to return the rental the following day (I took a slightly different highway route).

Trip 1
Day/Time: Saturday, between 3-4 PM
SoC when leaving: 100% (I think - the renter turned the car on to show me some infotainment stuff, and the AC was blasting for about 2 minutes)
Distance: 47.0 miles
Temperature: 73-76 F
Median speed: 50-55 MPH
EV Driving Ratio: 83%
EV miles (AER): 47 x .83 = 39.01 miles
Miles/kWh: 39.01 miles/6 kWh of usable capacity in the Prime = 6.5 mi/kWh

Trip 2
Day/Time: Saturday, between 11 PM-12 AM
SoC when leaving: 100% (I charged it myself, from flat to full, in about 5 hours and 35 minutes)
Distance: 22.6 miles
Temperature: 67-70 F
Median speed: 45-50 MPH
EV Driving Ratio: 100%
EV miles (AER): 38.88 miles*
Miles/kWh: 38.88/6kWh = 6.48 mi/kWh

*At least I think this is right: I started with an estimated EV range of 27.7 miles, I drove 22.6 miles, and I ended with an estimated EV range of 11.6 miles. That's a 16.1 mile range drop over 22.6 actual miles driven, so actual miles are 1.4037 greater (22.6/16.1) than estimated miles. 11.6 estimated miles of EV range left times 1.4037 means I really had 16.283 actual miles left. And 22.6 miles driven plus 16.283 miles left = 38.88 miles.

Trip 3
4 miles, no data

Trip 4
Day/Time: Sunday between 12:30-1:30 PM
SoC when leaving: 95% (estimated - I charged to full, then took my wife on that 4 mile drive, then plugged back in for another 30 minutes)
Distance: 44.7 miles
Temperature: 62-64 F
Median speed: 50-55 MPH
EV Driving Ratio: 87%
EV miles (AER): 44.7 x .87 = 38.889 miles
Miles/kWh: 38.889/6 kWh = 6.4815 mi/kWh


These three highway trips were all 1-2 miles of city streets to get to the highway, then 95% of the trip done on the highway, then 1-2 more miles of city streets. These were mostly 55 MPH state/county highways in Westchester County, NY, but even large stretches of I-95 have a PSL of 55 MPH, and I-87 has a PSL of 50 MPH as it feeds into NYC. I was going 50-55 MPH for most of the trips. In my experience, there wasn't so much a particular point when the traction battery was depleted and the car would "switch" completely and suddenly to hybrid mode. Rather, this "switch" was a gradual process that began after 31-34 miles of highway driving, and intensified thereafter with distance and load, but below a certain speed, the Prime was still capable of EV driving. For example, after about 31 miles on the first trip, and 34 miles on the third trip, the ICE started coming on, but only briefly, to help me get over hills, and then it would turn off again at the top of the hill. This ICE on/off behavior would continue until I got off the highway, and then the ICE would remain completely off for the city driving portion, and I would be able to drive in EV mode, even with a completely depleted battery. More than anything else about the car, I was particularly impressed with this feature of the Prime. Because this adds up to a lot of extra EV miles. When the EV range hit zero, the car was still driving in EV mode for significant stretches - as long as I kept the car under 30 MPH in city driving, it stayed in EV mode.

What's also impressive to me about this car: this was my first time ever driving a Prius Prime. And aside from 2-3 trips in a family member's Gen II Prius, this was my only other experience driving any Prius, period. And yet, I was able to manage 6.5 miles/kWh and 39 miles of AER, simply by driving the speed limit, and simply by doing most of my driving at a steady state on low PSL highways. This is a 56% improvement over the EPA estimated range. So imagine what a more adept owner could do with this car....

 

You sure packed a lot of test drive into that 24 hours, and from an apartment dweller, too! I'm impressed.

The only little area needing tweaking in your efficiency calculations is the accounting for the gasoline usage as it relates to the EV percentage you mentioned. Technically, some of the EV percentage/range once you switched into hybrid mode is generated from gasoline, so you either do what you do and with balanced accounting for gasoline, end up with crappy MPG, or you allow the AER to be quoted from the EV mode only, then account for the MPG in hybrid mode. If using blended modes, it'll get a bit more complicated and you pretty much have to account for everything based on charging kWh and gasoline consumed. The MPG display and reporting by the car and the Entune app is useless as it only accounts for gasoline consumed divided by the entire drive distance. Since you didn't post any MPG figures, I'm thinking you already knew this.

Nevertheless, you showed outstanding results in EV range and showed much of the capabilities of the car in hybrid mode where it can transition into EV-only segments. That's a lot of "FAS" without compromising speed.

 

Bill,

Sorry for the delay. But thanks for your thoughts. About your calculation tweaks...I didn't understand this part: "Technically, some of the EV percentage/range once you switched into hybrid mode is generated from gasoline..."

Why? I thought that when the Prime gives you an EV Driving Ratio of 87% for example, then this means that 87% of your miles were powered by the battery/electric motor, and 13% of your miles were powered by the ICE. It isn't that simple? Why would gas-generated miles creep into the EV percentage?

According to my math, I did 118.3 total miles, 104.5 of which were in EV mode (39.01 + 22.6 + 4 + 38.889), and 13.8 of which were in hybrid mode. I received the Prime with a "full" tank according to the gas gauge, but I forgot to top it off at the beginning of the rental to make sure it was 100% full (the owner could have driven it a few miles the morning before I picked it up, and the Prime is so efficient it would have still read "full"). But ignoring this oversight, I filled the gas tank before returning the Prime, and it took .3 gallons of gas. So the MPG in hybrid mode would be 13.8 miles/.3 gallons = 46 MPG. Perhaps this is the crappy MPG you're referring to?

I wasn't able to calculate charging kWh because I was plugged into a regular 120 V wall outlet....

Also, how are those front seats in the Chevy Bolt treating you?

Thanks.

Chris

 

So , if the engine is off during a glide, does the Prime call that EV use ?
Where did the energy for the pulse come from ?
My engine's off a fair amount of the time , but I don't call that "EV".

 

The prime looks like the most "nerd" fun, but from a cost and convenience standpoint:

- charging efficiency loss will add another 15% (roughly) to electricity use/cost
- 360 lbs of added weight will cost 4 mpg (roughly) -- a non-issue if you drive mostly in EV mode
- home charging (<.15c/kwh) will be cheaper than gas but commercial charging (>.20c/kwh) likely won't be
- other than home (in your own parking spot/garage) charging -- is it worth chasing down 6 kwh at a time? Depending on the individual, it might be -- for a while.

 

I hope Wayne's and Edwin's replies helped. A quick experiment you could try if you get a chance at another test drive is to start with a full battery, reset the EV% (I haven't actually seen this display except when I was in the 2012 PIP; haven't felt the need in the Prime), immediately switch to HV mode and take off. After a few miles of normal driving in HV mode with the engine shutting off on its own when not needed, you should see an EV percentage that would not be zero, which would have been the case based on your earlier supposition. This EV% came from burning gasoline, assuming your battery stays full. The Ford Energi models and I presume hybrids also would have a similar EV% display.

The way these new hybrids/PHEVs get such good MPG in hybrid mode is the automatic pulse and glide, even with a constant, moderate speed on the highway. Automatic FAS when terrain and speeds and battery levels allow. So... you would expect a certain EV% from this mode of operation coming from burning gasoline.

The seating is fine for me (5' 6", 170 lbs) and I have not felt any discomfort so far in about 1700 miles of driving. I like the cloth seats; I didn't go for the high-end trim. The bottom seat cushion is adequate in support, but fairly flat and gives little. The seat back feels good to me with side bolstering keeping me planted in the middle. I don't use the arm rests much in normal driving. It is a bit of a reach for the driver door arm rest. The middle console feels hard on my elbow when I rest on it. The top of the center console conveniently slides forward and backward, though.

 

OK, that all makes sense - thanks for those explanations. It's too bad though....because what's the point of an EV Driving Ratio if the calculation is wrong and you just have to do the math on your own....

I've heard the cloth seats in the Bolt LT are more comfortable than the leather ones in the Premier. I'm going to try to rent a Bolt for 24 hours soon and find out for myself....

 

Android auto? Don't have iPhone. (Until Apple makes iPhone open source OS like Android.)

 

And tamed styling.

 

Wow ! ! New sun visor extender !

Needs Android Auto. Edwin doesn't own any Apples. Never have, never will.

But there's a lot of goodness here.