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Electric car saga: Mercedes B 250 e vs. BMW i3 94 Ah
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Electric car saga: Mercedes B 250 e vs. BMW i3 94 Ah

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Home Mercedes Benz B-Class Electric car saga: Mercedes B 250 e vs. BMW i3 94 Ah

Mercedes B 250 e combines the spacious van body of the B-Class with the powerful drive train of Tesla’s electric car Model S. Meanwhile, BMW has updated its own i3 electric small MPV with a bigger battery which increases its range by a whopping 110 km. Can it beat the Mercedes? FIRST COMPARISON TEST.

Of course, we could complain about missing subsidies and range anxiety or even philosophize about the low oil price, which currently plays a major role in the predominance of conventional combustion engines. Yes, electric cars are still in their early ages: on a market of more than 15 million cars, less than 1% of all new car registrations in Europe are accounted by zero emissions vehicles. But all lamenting does not help, after all manufacturers have to gradually electrify their fleet, in order to implement the ever stricter CO2 requirements.

Comparing identical cars can be quite a challenge in the field of electric cars, where true segments are not yet fully segmented and the Mercedes and BMW tested could not, indeed, be more different. BMW chose a radical approach, creating the i sub-brand from scratch on a platform merging two separate modules: the Drive structure made from aluminum provides the basis for the chassis, battery, engine while the Life structure (mounted on top of the Drive module) consists of the passenger cell carved in CFRP – plastic reinforced with carbon fiber. Hence, the i3 tips the scales at only 1.320 kg or 405 kg less than the 1.725 kg B 250 e. Of course, we should not forget that at 3,99 m long, the i3 sits a full class below the 4,35 m B-Class.

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The i3 is a B-segment MPV and the B 250 e is a C-segment van. This explains why the trunk volume is twice as big in the Mercedes (501-1.456 liters versus 260-1.100 liters for the i3) and space is vastly inferior too in the BMW (both head and leg room) which can seat only two adults in the back as opposed to three in the B-Class. BMW compensates these shortcomings with the easier access provided by the suicide doors format and the missing central pillar. There are no window frames as homage to old-school coupes, but the i3 also comes with an unexpected twist: the rear doors cannot be opened unless the front ones are open first, so passengers sitting on the back seat can only exit if the driver gives them a hand.

Due to the lithium-ion battery mounted under the rear seat, the vehicle floor had to be placed four centimeters higher in the rear of the B 250 e, which is why passengers have to bent their knees a bit more than in the conventional B-Class. In addition, the sliding rear seat fell victim to the battery implantation. However, five people still travel comfortably in the family-friendly Mercedes. The rear seat can be folded in the 1/3-2/3 format and integrates a central arm-rest, while in the BMW there is no such option and the upper part of the bench can only be divided in half. Once folded away, the rear bench creates a flat loading surface in the i3, but surprisingly not the same can be said about the B 250 e. Both cars offer high driving positions, showing their MPV roots.

Styling-wise, the i3 clearly leads the pack. BMW invested 6 billion euro to offer an entirely unique model and we are not just talking about the sci-fi design. Praise should also go to the exotic construction philosophy and the mix of high-tech (CFRP) and recycled materials. The Mercedes on the other hand looks and feels like any other B-Class, retaining the practical advantages but also the benign looks of its conventional brother, built on the same production line as the future-proof B 250 e.

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The interior layout of the two cars follow the same recipe: classic for the B-Class versus an UFO inspired dashboard in the i3. In the Mercedes, everything is familiar from the normal model. But there are some differences too. The rev-counter is gone and its place is swiftly taken by the more appropriate power indicator showing the instant kW output. The available range is displayed on the small display mounted between the speedometer and the aforementioned power indicator. If the shift knob is still placed on the steering column, just like on any other Mercedes, the accompanying paddles do not select the gears anymore (only one gear available), but the distinct levels of regenerative braking functionality, ranging from the most efficient (and brutal) D- to the less intrusive D+ and D Auto. In the BMW, the energy recuperation severity cannot be selected separately – the settings differ in each driving mode, in Eco Pro+ the car braking more abruptly. Instead of the usual C, E and S driving modes influencing the engine response, the B 250 e offers its own flavored settings: E (Economy, maximum 98 kW available), E+ (Economy Plus, maximum 65 kW and 110 km/h) and S (Sport, full 132 kW power). Pressing the range plus button (small battery sign), 30 extra kilometers can be tickled out of the battery (the wear protection is temporarily deactivated).

Open the door of the i3 and you will easily mistaken the BMW for a smaller Enterprise command deck. The asymmetric dashboard and the forward-pushed windshield create an airy, show car feel, while more classic BMW traits like the 10,2-inch iDrive screen or the rotary control knob (virtually identical to the ones found in any other BMW) keeps the ambience grounded to the present. There is also a dedicated eDrive display mode, showing relevant data about the battery, energy recuperation history, instant propulsion or range. A second TFT display replaces the speedometer, while the shift knob is mounted on the steering column (right side) and is controlled through an interesting rotary motion. The materials adorning the interior are also decidedly futuristic: recycled fabrics, wool and bamboo wood. The Driving Experience Control commands for the adaptive drive train couldn’t be missing, of course. There is no Sport, but only the greener Comfort, Eco Pro (maximum 90 km/h) and Eco Pro+ (maximum 90 km/h, no air-con or heated seats, most intense and efficient regenerative braking).

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Mercedes van with Tesla power

The B 250 e comes with a particularly interesting ace up its sleeve: the drive train supplied by Tesla itself. Its asynchronous electric motor creates 132 kW (179 hp) and 340 Nm of torque, 9 hp and 90 Nm more than the synchronous engine of the i3. In front of the rear axle, where the gas tank used to sit, Mercedes engineers have grafter the Li-Ion battery pack with a capacity of 28 kWh. At BMW, the slightly smaller battery (27,2 kWh) is mounted right in the center of the chassis. Unfortunately, Mercedes renounced the possibility of charging the B-Class from the DC continuous supercharger network that Tesla is currently building on motorways across the world. With the gigantic charging power of 120 kW, 100 kilometers of range could have been obtained in about five minutes. Instead, the B 250 e can only be charged from 220V home networks (9 hours) or 22 kWh alternative current stations (2,4 hours).

If equipped with the optional double AC/DC connector, the i3 is also compatible with 50 kWh continuous current high power chargers (CCS) which reduce the refill time to only 39 minutes. When connected to a 220V outlet, the i3 recharges in 9,5 hours. From 22 kWh stations, the BMW needs 7,5 hours. This is because as standard, the i3 can only sip 3,6 kWh. With the optional fast charging pack (990 euro), the BMW can take in 7,4/11 kWh and the charging time goes down to 3,7/2,7 hours. The Mercedes comes with both house outlets and alternative current compatible cables, while BMW asks 242 euro for the later.

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The B 250 e surges to 100 km/h in 7.9 seconds, 0,6 seconds slower than the 405 kg lighter i3. Still, the 140 km/h mark is hit quicker by the Mercedes. Despite the 90 Nm deficit, the BMW is not only faster but also more responsive, more eager to speed up. No wonder, because the electric motor designed by BMW cleverly uses an additional magnetic principle (reluctance) that extends the torque band in the upper range, thus compensating for the power advantage of the B 250 e.

The spirited drive is also motivated by the rear-wheel drive format, and the i3 turns eagerly like a small go-kart with the smallest steering wheel movements. The propulsion format is different and this clearly impacts performance and driving fun: in the Mercedes, the engine is mounted in front and drives the front axle, in the BMW, the engine sits in the rear and sends power to rear wheels. BMW says rear-wheel drive is optimal for electric cars, as the high torque available from virtually zero rpm is transferred more efficiently to the ground in this format – with minimal traction loss. With its wide 18-inch wheels (19-inch pizza-like wheels on the i3), the Mercedes is just as skilful (compared to the regular B-Class), always comfortable and safe but less involving on twisty roads with its sensitive but unruffled steering. The weight penalty also takes its toll. The ESP (DSC) system is quite intrusive, in both cases. If electric cars are already expensive, they should at least be fun to drive too – and that is exactly what the BMW does.

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But, how much can you drive in real life? With the new, bigger 94 Ah battery (60 Ah in standard guise), the i3 now offers a range of 218 km, up from 135 km, which is the equivalent of a 50% increase of autonomy. In comparison, the B 250 e manages to drive 159 km in real traffic conditions. The mixed energy consumption registered in the BMW was 15,1 kWh as opposed to 23,8 kWh in the Mercedes. Both values were measured in the middle ground E (B 250 e) and corresponding Eco Pro (i3) driving modes.

Costs

BMW wins with a 3.000 euro price advantage. Customers have to pay for the new 94 Ah battery a surcharge of 1,200 euros compared to the 60 Ah i3, so the Bayer with large battery costs 36,150 euros. If you want to swap your small battery now for the big one, you have to dig deep into your pocket and pay around 7,000 euros. The Mercedes is more expensive at 39,151 euro, but also more practical and spacious. Taking into account the alternative current charging cable (242 euro) and faster charging package (990 euro), optional for the i3, the B 250 e is roughly 1,500 euro more dear than its Bavarian rival.

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Conclusion
1. BMW i3
The i3 drives extremely spirited and enthusiastic, consumes the least and has the biggest real life range. However, it offers the smallest interior space.

2. Mercedes B 250 e
To build a good green model, you do not have to reinvent the car, but offer a lot of space and safe driving behavior. High charging time and price.

Technical Data

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