I'm driving a 2018 Prius Prime (plug-in). What do you want to know about it?

[MetroMPG]

I know 2 people who have bought the current gen Prius - one regular, one plug-in.

In both cases, the local Toyota salesman told them: "Use B-mode on the shifter to save even more gas when coasting! It increases regen."

Bad advice!

Yes, B-mode it increases regen, but not to any level that can't be achieved simply by pressing the brake pedal lightly.

Worse, in the regular Prius, B-mode also spins up the engine (without adding fuel) for extra drag. So if saving fuel is your goal, you're in fact wasting energy by using B-mode and converting kinetic energy to heat (ICE friction), compared to just using the brake pedal.

PRIUS PRIME B-mode

I wasn't 100% sure if the Prime behaved in the same way, so I tested it this week with the ScanGauge.

Interestingly, B-mode behaves differently in EV (charge-depleting) mode than it does in normal hybrid mode. According to the ScanGauge, it will spin up the engine in hybrid mode, but not in EV mode. (Tested only at city speeds.)

My Prime friends had been using the car almost exclusively in hybrid mode, and also using B-mode often when decelerating. This new info will help them save a tiny amount of gas.

[redpoint5]

How about hybrid mode EV speed limits? In my plug in, I can go up to about 44 MPH with the traction battery depleted (hybrid mode) with the engine off, so long as the battery charge is sufficient. If I go faster, or the minimal amount of battery charge depletes, the engine spins up.

[MetroMPG]

I *think* the Prime uses its higher speed limit for ICE-off when in hybrid mode. But I didn't confirm that with the Scangauge.

I returned the car Thursday. Remind me next time!

[Vman455]

Originally Posted by redpoint5

I doubt it. My Gen III plug-in will shut the engine off below 44 MPH when the EV range is depleted as long as there is sufficient battery charge and not much power is needed. The engine comes on above those speeds regardless. With a full EV battery, the car will go up to 62 MPH with the engine off.

At 84 MPH, the power requirements great enough that running the engine is efficient.

I would be curious what the max speed on the Prime is to shut off the engine when the EV range is depleted.

So yours turns the engine on at the same speed as the non-plug-in Gen 3 when it's out of EV range...interesting. That would make sense that the Prime does the same then.

I discovered in 2016 (when I took the Prius out West, where the mountains are!) that, if the traction battery on a non-plug-in gets above 78% charge or so, it will run electric-only past the middle bar on the display, just like the PiP. That was surprising, and I wonder if the Gen 4 will do the same.

[MetroMPG]

It was showing a lifetime reading of 5.1 L/100 km (46 mpg US) when I picked up the car (with ~22,000 km on it).


I put about 250 km on it in a week (mostly EV kms), and returned it with the lifetime meter showing 4.9 L/100 km (48 mpg).


Hybrid mode (gas) fuel consumption was ~3 L/100 km (78 mpg, per the onboard display) using very MPG-friendly speeds & techniques on the back roads.

[redpoint5]

How is the friend only getting 46 MPG? I realize Canadian winters can really affect efficiency, but plugging in should at least offset that.

My gen 3 agerages 50 MPG in hybrid mode, and quite a lot more when factoring in the EV miles.

[MetroMPG]

They haven't been plugging it in, that's how. :^D

They live in an apartment with no outside plugs. Looking for a house.

[redpoint5]

I remember you saying that now... my Prius plug-in lives with my parents for now while we're in an apartment. My parents drive a car up to my grandma's house 400 ft away, only to swap to a pickup truck to get her lunch/dinner.

At least now they are doing that 400ft on electricity. I bought a Segway thinking they could use that rather than a vehicle.

The truck would never be driven if it weren't for the lunch runs.

[aerohead]

Originally Posted by MetroMPG

It's a 3.3 kW charger.

It looks like it won't be hard for me to beat the official EV range (40 km = 25 miles).

• 40 km = "EV distance to empty" displayed after top-up charge, as of first thing this AM
• 23 km = distance I've driven so far today
• 25 km = "EV distance to empty" currently shown

Hmm... 23 + 25 > 40!

That's all sub/urban driving in my sleepy little city. Eco-driving, not hardcore hypermiling. Main eco techniques: gentle acceleration (when no cars behind); looking well ahead and coasting to as many stops/turns as possible (when not holding up following traffic). Conditions: warm weather (24C / 75F); windows open (no AC); "ECO" drive mode selected.

So it looks like 50-60 km = 30-37 miles of EV range is within reach in this driving environment.



Confused me there. I have read the Volt's engine sometimes drives the wheels at certain (higher) speeds, but only when the battery has already been drained and the ICE/generator is running. In EV mode (unlike the Prius), it's 100% electric, all the time. Am I wrong there?

I'll apologize if this is redundant info,but I think the VOLT is a parallel hybrid,with no mechanical connection between the engine and drive wheels.It can only provide electrical power to the electric motor,when the pack goes below its design threshold.

[redpoint5]

Originally Posted by aerohead

I'll apologize if this is redundant info,but I think the VOLT is a parallel hybrid,with no mechanical connection between the engine and drive wheels.It can only provide electrical power to the electric motor,when the pack goes below its design threshold.

That describes a series hybrid, which I used to believe the Volt was. Turns out the Volt is a parallel. The 2nd gen even more so than a Prius since it has an extra clutch that (I believe) allows both Motor/Generators to be used as propulsion motors.

The Voltec drivetrain has three power converting elements:
Primary traction electric motor/generator, provides good acceleration for driving at lower speeds and regeneration for braking, its maximum output of 111 kW setting the maximum output of the whole system.
Secondary electric motor/generator, works primarily as generator capable of producing 55 kW or when necessary acts as a motor assisting the primary electric motor.

Internal combustion engine of 63 kW power, engaged when the batteries reach the predetermined threshold. These units are connected via a planetary gear and three electrically controlled hydraulic clutches to provide power output for propulsion in any of four programmed operating modes:

Single motor electric – The primary motor runs solely on battery power, maximum propulsion power is 111 kW.

Dual motor electric – At higher vehicle speeds the secondary motor engages over the planetary gear such that it reduces the speed of the primary motor. This facilitates higher efficiency and better mileage for the combined system, without increasing the maximum power.

Single motor extended – The battery reaches its minimum charge, which triggers the combustion engine. The engine drives the secondary motor as a generator, via the charging electronics, to keep the minimum battery charge level. The primary motor can still provide its 111 kW for short acceleration, albeit not sustained.

Dual motor extended – The electric motors are used again in dual configuration with increased efficiency at higher speeds. Additionally the gasoline engine contributes propulsion power via the planetary gear. While power is drained from the battery the amount is less than in mode 2 for the same propulsion power, thus extending the range.