Smart electrifies all its models

While the rest of the product planning departments at the world’s car-makers scramble to find ways to extract battery-electric prices for small cars, Daimler is already there.

So the product planners in Sindelfingen aren’t exactly sitting on their hands, but two decades of losing money on the expensive smart city-car brand look like they might finally pay off.

Like the Mercedes-Benz A- and B-classes, all smarts were conceived with electric power in mind and the new one, which made its debut at the Paris motor show this year, will be the fourth generation of zero-emissions smart fortwo.

But it goes further than that, with smart now the only car brand in the world to offer electric versions of every model it makes, including what it (somewhat tenuously) claims is the only BEV (battery-electric) convertible in the world.

"The smart is the perfect city car, and with electric drive it becomes a little bit more perfect", smart boss Dr Annette Winkler said.

"This is why we will soon be offering our entire range – smart fortwo, forfour and even our smart cabrio – as all-electric versions.”

The €21,940 fortwo will be the cheapest of the electric smarts in Germany, followed by the €22,600 forfour (which looks like far better value than it does with petrol power) and the fortwo cabrio is easily the most expensive, at €25,200.

Sharing an enormous amount of technology with Renault’s Twingo hasn’t hurt the electric smart’s development path, not least because it gave smart access to a five-door hatch.

At the core of the three-model range (fortwo, fortwo cabrio and forfour) is a separately excited three-phase synchronous motor, delivering 60kW of power and 160Nm of torque.

Like ICE (internal-combustion engine) smarts, the motor in all three models sits over the de Dion rear axle. Unlike the ICE smarts, there is no dual-clutch transmission nestled alongside it. Instead, there is just a single gear and when the driver selects reverse, the smarts simply run the electric motor backwards.

This reversible single-speed drive system is claimed to be a bonus in heavy traffic and is built on the same Renault production line in as the Twingo’s setup, in Clèon, France.

The motor’s rotor is magnetised whenever current flows, with the energy flow from the high-voltage, lithium-ion battery governed by (what used to be called) an ECU that also controls the entire drive system.

All three versions share the same 17.6kWh battery pack sitting beneath the front seats or, in the case of the two-door versions, the only seats.

Built by Saxony’s Deutsche Accumotive, Daimler’s wholly owned battery subsidiary, the pack uses 96 flat cells and its chemistry has been improved to the point that Daimler guarantees that the quoted capacity and power output rates will remain as the cars’ minimum eight-years or 100,000km.

Deutsche Accumotive also made the battery pack for the third-generation BEV smart fortwo, though this one outstrips it by offering 160km of range on the NEDC cycle, limiting the top speed to 130km/h to help the range.

While the coming wave of premium electric cars will use any number of custom-designed alloy cases for their battery packs, the smarts sit theirs in a cage of high-strength steel tubes.

The cars will retain the standard clever features from existing smarts, including a 6.95-metre kerb-to-kerb turning circle for the 2.69-metre fortwo and fortwo cabrio.

The cars receive an upgraded on-board charger that halves the recharge time to two-and-a-half hours in Great Britain and the US. There will be a 22kW fast charger available from next year for Western Europe, allowing the cars to utilise three-phase power to cram an 80 per cent charge into the battery in just 45 minutes.

Another tweak for keeping the BEV smarts moving is an anticipatory radar-based energy recuperation system to minimise wasted braking energy by harvesting as much energy as possible.

Besides a softer throttle response and a lower top speed, the smart’s more frugal ECO mode also gives up five different rates of recuperation urgency, converting kinetic energy into electrical energy.

Its radar monitors the surrounding traffic and lets the car coast if there’s no traffic, then uses the electric motor as a generator to harvest energy depending on how quickly the car needs to wash off speed. The enthusiasm with which it harvests energy depends on the battery’s temperature and state of charge, though smart was unwilling to furbish further details.

Another way it saves energy is by forcing the climate control to reach a pre-set temperature while the car is still attached to the charging station, and that can be adjusted via a smartphone app, along with two preset departure times.

It has also moved to counter concerns about pedestrian interaction with a quieter generation of urban transport by fitting the US cars with a weatherproof speaker in the grille. The speed-variable system works predominantly below 30km/h and will be optional in Europe, where it will have a manual override switch.