In the process of checking out the electric vehicles at this year’s EVS26 Symposium in Los Angeles, Consumer Reports has observed that purpose-made EVs trump ones adapted from conventional internal-combustion models.
The influential publication called out the Chevrolet Volt and Ford Focus Electric as being among those that are “full of compromises” having been “built from gasoline models,” thus having higher center of gravity and sacrificing interior space. The Volt, CR observed, shares its chassis with the Cruze, and the Ford Focus EV is based on, well you guessed it, the Ford Focus.
“The primary reasons to base an electric on a gasoline platform is to save money and race to market-both fair business objectives,” CR said. “But that approach smacks of lower commitment by those automakers to building electric cars.”
In contrast, CR praised the design philosophy of the Nissan Leaf and Tesla Model S better as these pack batteries low under the floor.
“The sleek Tesla Model S has impressive space efficiency, with a flat interior floor that’s wide open in front and gives generous legroom in the rear,” CR said. “It has a spacious hatchback big enough for a rear-facing third-row seat, and a trunk up front where the engine would go.”
And believe it or not, CR gave kudos also to the Coda electric sedan. Even though it is based on a 2000 Mitsubishi Lancer, “the company found a way to sandwich most of the batteries under the floor,” CR said.
After reading through Consumer Reports analysis, one could just as well summarize it by saying the publication appears to be increasingly coming to favor the inherent design advantages of the EV “skateboard” design, or the nearest equivalent.
Tesla Model S “skateboard” chassis.
The advantages of stowing batteries low and out of the way are several. For one, it does not necessitate sacrificing a fifth seat passenger as the Volt does. Nor does it sacrifice usable trunk space such as the Focus EV does by loading batteries in the back. In fact it leaves engineers free to design the vehicle with much less encumbrance from bulky batteries fitted into a conventional chassis.
And from a handling, braking and ride quality standpoint, the argument is made that the lower center of gravity afforded by flat batteries slung along the floor is the way to go.
That is, the heavy batteries ride low, and Tesla for one, has gone on record saying its Model S will be a superb handler among sedans in part for this reason.
“We’ll be looking for more purpose-built electric cars in the future,” Consumer Reports said, having inadvertently defined a new metric.
But while true the Cruze and Volt share much, it’s also been said GM built the Volt based on its 2007 concept vehicle and it has been called purpose built in some respects. Perhaps some could say it was sort of purpose built, but GM based it on a conventional design, and also spun off the Cruze that has since become a cash cow, while the Volt took the place of a halo for the New GM.
Nissan places batteries less obtrusively below the Leaf’s floor.
The Ford Focus EV is another issue, however. It undeniably came out of an existing model, has been called a high-efficiency “compliance car” to improve the company’s fleet fuel consumption and emissions average, and Ford has shown a nominal commitment to it thus far, so we’re more inclined to see CR’s points there.
Not addressed by CR however is crash-worthiness. Those batteries and related hardware are expensive, and would compound the complexity of any body shop repair if smashed in an accident.
Aside from much-amplified reports about the Volt’s battery potentially smoldering if crashed and left still charged, its battery is shielded from side-impact damage by being so buried in the center of the car. So that might even be an advantage for this one aspect of post-crash repair – depending on how hard it is hit, of course.
On the other hand, we’re not sure how protected the batteries would be from the side with electric vehicles with a skateboard design. No doubt all vehicles must be designed to protect occupants to acceptable standards – in fact the inherent weight of electric vehicle tends to help them do comparatively better in crash test results – but how would their electric underpinnings fare after an impact?
Maybe OK? Maybe not? More light will be shed on this question after these vehicles have had more time on the road, and more of them have had enough real world crashes for patterns to emerge.
But what do you think? Consumer Reports opens its article saying “The difference could not be more stark” than between converted ICE vehicles and those made from their inception as EVs. Is it right, off base, or is the truth somewhere in the middle?
This entry was posted on Tuesday, May 15th, 2012 at 5:55 am and is filed under General. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.