Tesla Motors: The Pros and Cons of Plug-In Hybrids


By now, most of you must be familiar with electric car startup Tesla Motors (see links at the bottom of this post); They caused quite a stir when they announced that they would start selling an electric car that is faster than a Ferrari but twice as clean as a Prius (with the average US electricity grid mix of sources charging it, it can be even cleaner) in 2007. One of the things that we appreciate about the company is their transparency: They write about the reasons behind their technical choices on their blog. One of their entries is about plug-in hybrids (PHEV). They list pros and cons and end up making a pretty good argument in favor of electric vehicles (EV)...


* A plug-in hybrid definitely allows you to drive on non-petroleum energy. Depending on the battery size, this could be a substantial amount of your daily driving.

* A plug-in would allow you to take a long trip without waiting for an electric charge – it simply operates as a gasoline car (albeit with a heavy load of batteries onboard) once the electric range is exceeded.

An argument could also probably be made about the cost of plug-in hybrids vs. the cost of electric car, but it might not hold for too long if we consider Tesla's plans to introduce affordable electric cars in the coming years. We'll have to wait and see how low the price of plug-ins will be once the "early adopters" phase is over.



* A plug-in hybrid (with a small battery pack) is much more abusive to the batteries than a pure electric car is. This seems counter-intuitive, so bear with me. Let’s say your particular battery design is good for 500 full charge-discharge cycles. On a pure electric car that goes 250 miles per charge, the battery pack should last 500 X 250 = 125,000 miles. On the other hand, a hybrid with, say, a 50 miles range will cause the capacity of the batteries to drop much sooner: 500 X 50 = 25,000 miles.

We're not sure about this one. The small battery packs in the current hybrids can last the life of the vehicle. Wouldn't there be a way to make the batteries in plug-in hybrids last as long? Maybe that would reduce the electric range further (by avoiding deep discharges?), though.

* Of course, you could put a full Tesla Roadster-sized battery pack into a plug-in hybrid – but then the car is even more expensive – a full electric drive train PLUS a full gasoline engine. (And the weight of the gasoline engine will reduce electric range.)

* Any hybrid is still subject to the complexity of gasoline engine maintenance: oil changes, smog checks, tune-ups, etc.

* From the perspective of a small manufacturer like Tesla Motors, a hybrid drive also means another nightmare of legal requirements in the form of EPA regulations, CAFE reporting, servicing, mandatory emissions component warranties, etc.

* A hybrid has double the safety concerns: a pack full of charged batteries AND a tank full of highly flammable gasoline

*It seems so much more practical to use a purely electric car for the 99% of our driving that is less than 250 miles per day, and just take our other car (or rent a car!) for the occasional road trip. That way, we don’t lug around a whole gasoline drivetrain every single day just to be ready for the rare long-distance trek.

While we still think that plug-in hybrids will be an improvement on the current hybrids and make a big difference, we can't wait for the second and third EV models by Tesla and for other electric car companies to jump in the fray. The future is electric, it's just a matter of how fast we get there.

Photo Credit: Ben Stewart, Popular Mechanics
::Hybrids, Plug-in or Otherwise, ::The Tesla Roadster: Electric Sports Car, ::Tesla Motors: Affordable Electric Cars are Coming, ::Tesla Roadster: The Electric Car that Redefines "Power" (Part 1), ::Tesla Roadster: New Power to the People (Part 2), ::Not All Hybrids Are Created Equal