Absolutely stunned at overall MPG with the new 2021 Prime!

To get the real mpg, you need to subtract your EV driving. The battery state of charge (SOC) typically decreases in HV driving, and you need to account for that. Also, the MFD inflates the actual mpg by 5–10%.

All this said, my actual mpg is over 70 mpg. If I don't account for what I listed above, I typically see over 80 mpg on the MFD every time in HV driving. Warmer weather is pushing it over 90 mpg; so, the actual mpg is approaching 80 mpg in warmer weather.

If I get caught in stop-and-go traffic, I get something like 115 mpg (over 100 mpg after the corrections listed above), which is amazing, easily beating motorcycles!

 

You get 80 in trips done exclusively in HV mode? And even 115 in HV only mode when in dense traffic? How?!?

 

I broke in the internal-combustion engine very slowly. Crawling freeway traffic is when the Prius Prime's HV fuel economy shines most. I do employ hypermiling techniques, trying to stay below 57 mph on the speedometer when I can.

 

I guess I underestimate the hills around here and the elevation (2000m / 6500ft)

 

I get about 66 to 72 without a charge on the highway

I can get about 34 miles on a plug in too.

It really is an incredible car and I'm shocked thinking of what they will be like with solid state batteries

 

In Los Angeles, it is not hard to find a Prius Prime that has never been in traffic. My 2021 Prius Prime still had all the plastic protectors on it, clearly no customers had ever been in it, with only 4 miles on it from driving around the ports etc. This is important because test-drivers could stress and improperly break in the internal-combustion engine. I didn't even bother to test-drive it, as already had a 2020. After the paperwork was completed, I made the entire 17-mile trip home on surface roads, avoiding the freeways, so that the proper engine break-in would be initiated. in the first 1000 miles, I never exceed 55 mph. So, I think having bought an entirely virgin car and then breaking it in slowly helped me obtain amazing fuel economy.

 

Nop, Prius Prime has only two batteries. One lithium high voltage traction battery and one 12v regular flooded lead-acid battery. There are no separate batteries for EV and regular HV drive. It's all in one big battery, just a portion (about 14% of SoC) is reserved for the HV mode operation, the rest is used for the EV mode except the reserve portion which the car would not touch. Whatever you cited is wrong information on current models of Prius Prime. Maybe on per-production models, although this is the first time I have read it.

 

Wasn't aware this was a thing

Oops

Drove mine with 54 miles on it (was brought from another dealer) 1200 miles over a 2 week period going to New England

Had the car a month or so has 2400 miles

Whoopsie

 

As pointed out before, this is completely wrong. There is the 12V lead-acid aux battery that wakes up the computers and there is the 8.79 kWh traction battery. If there is enough charge in the traction battery, you can drive the Prime in EV mode. If the state of charge goes below about 23% actual (as opposed to what's on the display), the car goes to HV mode on its own. One battery, different states of charge.

 

Understandable mixup now that you reveal your source. By and large, car salesmen are total ignoramuses.

There's a lot of debate about whether HV mpg is better with some range in the battery. It's practically impossible to prove one way or the other. Still, I'm also inclined to think that it helps. But it's not significant enough to be sure. It might be the weather or the phase of the moon.

 

The low threshold SoC for the EV-HV switch is more like 14% actual. I have checked the actual SoC of the traction battery using the Hybrid Assistance app as the EV range depletes as shown in the graph below. The 0-100% range on MID is actually 14%-84% SoC by HA.

 

That's probably correct to some extent. In any case, the SOC never comes back to where you started during HV driving, which means you are always stealing some EV driving and cheating, but this is actually good for the environment. Typically, I lose about 5% during each HV trip. If you fully depleted your EV SOC allowance, the system would have to return what is borrowed and couldn't steal SOC anymore, which would hurt your HV mileage both directly and indirectly, the former because the system can no longer cheat and the latter happening when you don't have SOC available when the system needs it because the battery has been drained to the danger-zone limit.

As a side note, I did witness the SOC coming back up to 1% or 2% after dipping to --, which I had thought never happened.

 

Interesting. I was going from memory from watching the videos by @john1701a. Seems like his car was switching to HV at 23%. I'll have to go back and check when I get some time unless he spots this and saves me the time.

 

When it dips below 14%, you see the switch from EV to HV.