Mercedes-Benz B-Class drives well, but not far, on Tesla power train

Mercedes-Benz fits a Tesla battery pack to its 2014 B-Class Electric Drive, creating a comfortable driver with limited range.

Wayne Cunningham

Wayne Cunningham

Managing Editor / Roadshow

Wayne Cunningham reviews cars and writes about automotive technology for CNET's Roadshow. Prior to the automotive beat, he covered spyware, Web building technologies, and computer hardware. He began covering technology and the Web in 1994 as an editor of The Net magazine.

See full bio
6 min read

CNET editors pick the products and services we write about. When you buy through our links, we may get a commission.

Gradual acceleration, maintaining steady speeds under 40 mph, and carefully planned regenerative braking all help maximize range in electric vehicles. When I got behind the wheel of the 2014 Mercedes-Benz B-Class Electric Drive, I didn't practice any of those strategies.

Instead, I hammered it along a twisty mountain road and ended up with a dismal Eco score, according to the car, of 29 out of 100.

I put my inefficient driving down to both the car's responsive electric drivetrain, built by Tesla, and the route Mercedes-Benz chose for this press introduction of its all-new electric car. Most of the 52-mile drive was on a 65-mph freeway and a mountain highway with a steep ascent.

Despite my behavior, at the end of the drive the car showed 29 miles range left from its full charge of 85 miles at the start. I had only burned up an extra 4 miles of estimated range compared with the actual miles driven.

2014 Mercedes-Benz B-Class Electric Drive takes to the road (pictures)

See all photos

Mercedes-Benz held this introduction to the B-Class Electric Drive ahead of its sales release, which begins this summer in what are known as the ZEV (zero-emissions vehicle) states: California, Connecticut, Maryland, Massachusetts, New York, Oregon, Rhode Island, and Vermont. These states are mandating zero-emission vehicles from automakers. Mercedes-Benz intends to offer the B-Class Electric Drive in all states and Europe in 2015.

Compact minivan

The B-Class is one of Mercedes-Benz's European models, sort of like a compact minivan with room for five people and some luggage. The design is practical, if a bit frumpy. In Europe, this front-wheel-drive-format car comes with a variety of gasoline and diesel small-displacement engines, but the Electric Drive version is the only model planned for the US.

2014 Mercedes-Benz B-class Electric Drive

The 2014 Mercedes-Benz B-Class Electric Drive runs for about 85 miles on its 28-kilowatt-hour battery pack.

Wayne Cunningham/CNET

Rather than some skunkworks project, the B-Class Electric Drive felt like a finished car ready for the showroom floor. The switchgear felt solid and an LCD mounted on the dashboard showed the latest version of Mercedes-Benz's infotainment system, combining refined-looking maps for navigation with its recent in-car apps system.

Missing from the center LCD was any information about the car's electric drive system or controls for scheduling charging. On the instrument cluster, Mercedes-Benz replaced the tachometer with a power use gauge, and included detailed range and electricity use information on a small monochrome display. In a product briefing, Mark Webster, Mercedes-Benz general manager of e-mobility, said owners would get online accounts for their cars, letting them schedule charging and set climate control remotely from a PC, tablet, or smartphone.

Americans used to Mercedes-Benz as a luxury marque may feel let down by some of the appointments in the B-Class Electric Drive's cabin. I liked the look of the big strip of faux-wood trim across the dashboard, but the feel was pure plastic. Similarly, the four-spoke vents have a nice design, but the feel is light and cheap. Making up for these trim pieces, the power-adjustable leather seats were quite comfortable.

I wasn't surprised to find the standard Mercedes-Benz drive selector, a stalk on the column, in the B-Class Electric Drive, when I got behind the wheel. Selecting D, I found the car felt ready and willing to pull away from the curb, with a bit of creep programmed into its drivetrain. Mercedes-Benz is not subscribing to the single-pedal driving style promoted by Tesla and BMW.

Simple driving

As is typical with electric cars, driving was a simple matter of hanging on to the wheel and pushing the accelerator. With an electric motor driving the front wheels through a single-gear transmission, the car glided forward quietly and smoothly. Impressively, the accelerator programming prevented the car from lurching, as some electric cars do. At only 300 pounds heavier than a gasoline-engined B-Class, the car did not feel particularly heavy, either.

2014 Mercedes-Benz B-class Electric Drive

Mercedes-Benz replaces the tachometer with a power use gauge, while a monochrome display shows range and other information.

Wayne Cunningham/CNET

The B-Class Electric Drive gave me some options for driving response. A button on the dashboard let me switch between Efficient and Sport modes, the former having a kick-down switch on the accelerator to access full power. In either mode, I found that stomping on the accelerator from a stop elicited an extended chirp from the front tires.

This car also came equipped with paddles mounted behind the steering wheel, engaging different regeneration modes. Defaulting to a standard mode, which initiated a moderate amount of braking regeneration as soon as I lifted off the accelerator, I could also choose D Minus and D Plus, initiating more aggressive regeneration or letting the car coast.

Mercedes-Benz calls the more interesting regeneration option D Auto. This mode relies on a forward-looking radar to gauge the distance and speed of traffic ahead. When cars in front of me began to brake, the B-Class Electric Drive automatically initiated braking regeneration, slowing the car and recharging the battery pack.

My only problem with this feature had to do with my own expectations. I have driven many cars with adaptive cruise control, including other Mercedes-Benz models. When the B-Class Electric Drive automatically slowed due to traffic, I expected it to come to a complete stop. Instead, it would have rolled right into a rear-ender if I hadn't hit the brakes. Mercedes-Benz has such good adaptive cruise control on its other models, I don't know why the company didn't build it into this one.

The steering weighting felt good, with responsive action to the front wheels, but the Sport mode didn't change the steering response. As I would expect from the general design and platform of the car, it was prone to understeer, but most owners likely wouldn't put it through the paces that I did.

In freeway and city driving, the ride quality felt reasonably soft and competent, although of course not rising to the comfort level of an S-Class. At speed through some tight turns, the car held the road remarkably well, its run-flat tires retaining grip and its suspension limiting sway.

Low-slung weight

Contributing to the handling, Mercedes-Benz installed the 28-kilowatt-hour lithium ion battery pack under the floor, between the front and rear axles. In front, an electric motor capable of 177 horsepower and 251 pound-feet of torque drives the wheels. Tesla Motors assembles the battery pack, motor, and associated power control module, then ships these drivetrain components to Mercedes-Benz's B-Class factory in Germany.

2014 Mercedes-Benz B-class Electric Drive

The power control module, visibile under the hood, comes from Tesla.

Wayne Cunningham/CNET

A J1772 charging port sits on the left rear fender, where the fuel filler would be on a gasoline-fueled B-Class. Mercedes-Benz says the car only takes 3.5 hours to charge from a 40-amp Level 2 charger, which owners can install in their garages. However, Webster noted during the presentation that it would take more than 30 hours to charge the battery from a 110-volt source. The B-Class Electric Drive lacks any kind of fast-charging option.

Mercedes-Benz expects the EPA to give the B-Class Electric Drive an 85-mile range. However, cars equipped with the Range Plus option can get an additional 18 miles of range when the owner activates this overcharge feature when plugging in. Webster said that frequent use of the Range Plus option "could impact the life of the battery."

As I found from my drive, an 85-mile range seems completely realistic. I also noted the trip meter's statistic that I had covered 2.5 miles per kilowatt-hour.

Standard equipment

Mercedes-Benz announced that the base price of the B-Class Electric Drive will be $41,450, not including a $925 destination fee, putting it in a substantially higher price range than the base of $28,980 for a Nissan Leaf . Government incentives, including a $7,500 Federal tax credit, could bring the price closer to $30,000.

As with the majority of electric cars on the market, the 2014 Mercedes-Benz B-Class Electric Drive fits a fairly specific owner, a driver with a need for no more than 80 miles of daily driving and a place to plug the car in at night. Within those parameters, the B-Class Electric Drive feels like a good choice.

It's pricier than the Nissan Leaf, the most popular electric car currently on the market, but the B-Class Electric Drive offers more room and better standard amenities, such as blind-spot monitoring, collision warning, lane assist, parking assist, and navigation.