REEVs and PHEVs: A Distinction, or a Difference?

By · October 20, 2011

Volt and Prius Plug-in

Recently, at the EV 2011 VE conference in Toronto, I had the opportunity to drive the new plug-in Toyota Prius and the Chevrolet Volt back to back.  The differences in the electric-drive behavior of the two vehicles have the potential to catch people off guard as they weigh their EV choices.

GM is promoting the Volt as an electric car with a range-extending gasoline motor (REEV).  The car will deplete the battery to a certain threshold, then turn on the internal combustion engine (ICE) to recharge the battery and power the wheels.  During this charge depletion period, the driver can drive in any way she wants – jackrabbit starts, freeway speeds, a/c blasting – and the ICE won’t start until the battery hits a certain point.  If you do drive the vehicle like a teenager on her first drive without Mom or Dad, you won’t reach 40 miles.  You may not even get 20 miles, but the ICE won’t start until the batteries hit that charge depletion threshold.

With the Prius, it’s a slightly different story.  Toyota is promoting the plug-in Prius as a plug-in hybrid (presumably as opposed to an REEV).  The vehicle has an EV mode that favors the electric motor, but it also has a top speed of 62 miles per hour.  I say “favors the electric motor” because during a merge onto the freeway with a full battery charge, for example, you’ll hear the ICE start when your speed climbs to 63+ mph.  Even in the city, as I drove a Prius claiming 8 miles of EV range remaining (out of 15 miles total), when I tromped on the accelerator to get the vehicle to the 40 mph speed limit as fast as possible, the ICE kicked on to assist with acceleration and then promptly shut off again as I backed off.  I was definitely not driving like a typical EV or hybrid driver (more like that foolish teenager) – yet during my short test drive, the ICE ran for less than a minute. 

A few days later I attended a presentation by Chrysler on its Ram PHEV trucks.  Company officials referred to these vehicles as “Blended PHEVs.”  Blended PHEVs appear to be similar to the PHEV drivetrain of the Prius.  Unfortunately, I was not given the opportunity to drive the Ram PHEV to find out for myself. 

I suspect that there will be a lot of mainstream car buyers surprised by the fact that the Volt and Prius plug-in do not behave the exact same way when in EV mode.  And while I don’t hear the complaints about GM’s marketing the Volt as a range extended electric car nearly as often as I did earlier this year, I doubt this comparison would quell that anyway.  Ultimately, I doubt the plug-in Prius PHEV characteristics will turn off most drivers who are unlikely to use gas for 15 miles when driving the vehicle “properly.”  In fact, I’m more inclined to think the price and the huge number of current Prius owners will tip the scales towards Prius’ success.

However, the Volt and Prius clearly demonstrate that the contrast between an “REEV” and a “PHEV” is a bit more than a semantic difference, despite the similar basic architecture.  Whether the distinction between PHEVs and blended PHEVs is significant (I assume a Volt would be considered a PHEV and the Prius and Ram blended PHEVs) … well, that I’ll leave to the marketers to try and sort out.  I’ve said it before, and I’ll say it again: Watch out for customer confusion ahead.

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