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Comment by rootusrootus | Hacker News Reader

An EREV is basically the worst of almost all worlds. It's a BEV with a motor tacked on. It ends up with a battery not a lot smaller than a pure BEV, so no real reduction in the cost of an expensive component, plus an engine and generator along with associated maintenance headaches. Not to mention the almost certain loss of cargo capacity.

I can't see myself ever wanting a Lightning EREV, for example, because of this exact issue. If I needed to tow, that would be the sole situation where it might hold enough of an advantage to matter. Aside from that, it will have (most likely) about 75% of the battery the BEV Lightning has, and it will lose the frunk, which is one of my favorite features. Plus, unlike my Lightning with it's 200K mile first required maintenance work, the EREV will probably have to be serviced every 10-20K miles. Ugh.

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The Chevrolet Volt is a representative EREV. Its battery is 1/3 the size of a Model 3's -- that's a lot smaller than a pure BEV. 50 mile electric range, 45 mpg on gas. These cars are now 10 years old (approaching 15 for the first generation), and out of the 3 known common issues for Gen 2 only one has anything to do with the gasoline engine.

The Volt is not an EREV, it is a plug-in hybrid. GM wanted to make it a series hybrid (EREV) but due to the inefficiency at highway speeds it does engage the engine mechanically to drive the wheels.

(Interestingly, the wikipedia page for EREV incorrectly cites the Volt as an example of an EREV, but the actual page for the Volt correctly identifies it as a plug-in hybrid.)

As an unrelated aside, it also has been abandoned altogether by GM and the only way to fix the battery is to find a third-party repair shop to work on it. Batteries are not available, and for the cars remaining under warranty coverage a battery failure results in GM buying back the car since they cannot fix it. Caveat emptor; IMO the resale value right now is much too high given that risk.

Off the top of my head, the only example I can think of for an EREV that actually reached production status (in the US at least, China excepted) is the BMW i3.

The Volt Gen 1 used the engine primarily to run the generator, although the mechanical coupling ability existed in Gen 1 as well. Gen 2 optimized the system to couple the engine to the wheels whenever it is efficient to do so, when an engine mode is selected or the battery is run out.

However, besides from the formal classification debates, I submit that the Volt meets the primary customer visible "EREV" behaviour: it drives like an electric car with the full available power (the engine never comes on) until the battery is depleted or a different drive mode is explicitly selected. All other PHEVs use the gas engine to assist when full power is called for by default, unless the "EV" mode is explicitly selected. The Volt, as far as I know, is the only EREV/PHEV that had that behaviour.

The only other example of a series EREV I know of where the engine is small and fully decoupled from the mechanical drive train is the Mazda MX-30R, which never made it to the US and was discontinued in EU and Japan after a short two year lifespan.

Yes, towing is a big potential case for EREV. A 600 mile EV truck (300 when towing) would need a 250kWh+ battery pack.

An EREV version could get by with 50-100kWh, which is also a lot less weight to carry. And would give plenty of power for driving EV-only for shorter trips when not towing.

> An EREV version could get by with 50-100kWh, which is also a lot less weight to carry.

It would most likely be closer to the top of that than the bottom. The standard range Lightning has a 98 kWh battery. So you can see what I mean, the battery would only be slightly smaller. Slightly less expensive, and slightly lighter -- but remember that you also have to add back in the weight of the engine and generator.

Dropping 150kWh+ of battery weight needed to perform the job is not slightly smaller. The Silverado EV in max spec gets 500 miles of range, 250 when towing, and the battery pack weighs more than a Honda Civic.

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