http://green.autoblog.com/2012/05/11/co ... n-comprom/
[IMG]http://www.blogcdn.com/www.autoblog.com ... fd-opt.jpg[/IMG]
When it comes to battery-electric versions of existing gas-powered vehicles, it's tough for those leopards to change their spots.
That's a conclusion from Consumer Reports, which says that the Ford Focus Electric and Chevrolet Volt are among plug-in vehicles marred by design compromises because they used platforms from existing gas-powered models.
The Volt, whose architecture stems from the Chevrolet Cruze, and the Focus EV both lack interior room and trunk space because the cars' larger batteries were crammed into spaces not originally designed to accommodate them, according to the publication. In contrast, models like the Nissan Leaf and Tesla Model S, which were always designed for electric powertrains, keep most if not all of their batteries underneath the car's flooring, increasing roominess as well as improving handling. Consumer Reports noted the Mercedes-Benz B-Class Fuel Cell vehicle as an exception because most of its powertrain components are also in the floor.
The topic of converted electric-drive vehicles vs. those that had always been designed as EVs is topical as many automakers rush EVs to the market to capitalize on growing awareness of electric-drive vehicles.
Earlier this month, Green Car Reports broached the topic of converted vs. purpose built EVs in an article about which EVs are being made for true production and which are being produced merely to comply with California's quota for zero-emissions vehicles. Green Car Reports concluded that converted models such as electric versions of the Focus, Honda Fit and Toyota RAV4 are being made merely for compliance purposes.
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Artigo original:
Purpose-built electric cars trump manufacturer-converted models
http://news.consumerreports.org/cars/20 ... odels.html
There are two kinds of electric cars at this year's electric vehicle symposium, fondly known as EVS26: Purpose-built electric cars, and those that have been built from standard gasoline cars. The difference could not be more stark.
Cars that have been built from gasoline models are full of compromises. Often the battery takes up much of the trunk space, as is the case with the Ford Focus electric. Or, as in the case of the Chevrolet Volt, it may even take up passenger space. (The Volt is based on the conventional Chevrolet Cruze.) Its inverted "T"-shaped battery runs through an extra-large tunnel in the car between the rear seats, eliminating the space for a center passenger, and limiting the car as a four-seater. The top of the "T" sits underneath the rear seats, but it still sticks out far enough to compromise foot access into the rear seats.
[IMG]http://news.consumerreports.org/assets_ ... o-4604.jpg[/IMG]
Purpose-built electric cars are much more space efficient, because they don't try to cram the battery into spaces that weren't designed for heavy powertrain components. Instead, most purpose-built electric cars use flat-format cells sandwiched under the whole floor of the car. This is the case with the Nissan Leaf, as well as several upcoming models at the public ride-and-drive session outside the Los Angeles Convention Center this week: the BYD e6 and the Tesla Model S.
Even the Mercedes-Benz B-Class fuel-cell, which is not strictly a battery-powered electric, as it runs on an electricity-producing fuel cell, houses most of its heavy drivetrain components in the floor. And it's very roomy and nice to drive.
[IMG]http://news.consumerreports.org/Ford-Fo ... -cargo.jpg[/IMG]
Either way, flattening the drivetrain components under the floor also gives designers flexibility to maximize the shape for other uses. 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. It has a spacious hatchback big enough for a rear-facing third-row seat, and a trunk up front where the engine would go.
Of course, there are exceptions: For example, while the Coda electric sedan is based on a 2000-model-year Mitsubishi Lancer, the company found a way to sandwich most of the batteries under the floor.
Putting the batteries under the floor has dynamic advantages, as well. Since batteries are heavy, they lower the center of gravity and spread it out, aiding handling, braking, and even the ride. Carrying that much weight around in the trunk can't do much for handling.
We'll be looking for more purpose-built electric cars in the future. The primary reasons to base an electric on a gasoline platform is to save money and race to market--both fair business objectives. But that approach smacks of lower commitment by those automakers to building electric cars.