Test drive Ruf ER Model A: Electric transport
Test Drive

Test drive Ruf ER Model A: Electric transport

The renowned Bavarian connoisseur of Porsche modifications and interpretations, Alois Ruf, is working at an accelerated pace to create the first German electric sports car, the ER.

Ruf is well known to car enthusiasts for its supersport modifications based on Porsche models, but few people know that its founder and owner's hobby is power plants. Alois Ruf already has three operating hydroelectric plants included in the German power grid, and now he is trying to combine business with pleasure. The child of the union of hobby and profession is called the ER Model A and has every chance of becoming the first functional electric sports car using the technical platform of the Porsche 911.

Unusual hobby

“Our original idea was just to find out if and to what extent there is enough energy from the on-board batteries to provide a sporty driving style and decent mileage,” Rufus explains as he aims for the project, adding: zero emissions from our US customers.” .

The need for concrete steps in this direction became apparent, and specialists from Calmotors - the California branch of the Ruf development - rolled up their sleeves. In place of the dismantled boxer engine and fuel tank of a conventional 911, American engineers installed a traction synchronous electric motor, resembling the drum of an automatic washing machine in shape and size and weighing 90 kilograms. The motor is AC powered, does not use brushes and develops a maximum power of 150 kW (204 hp). This type of permanent magnet units has a slightly higher efficiency (90%) than the more commonly used asynchronous models.

Instead of a tank

Lithium-ion batteries are distributed throughout the vehicle. Their total number is more than 96, the connection is serial, the weight is half a ton. The impressive power supply is designed by the Chinese company Axeon and has an electronic system to control and manage the voltage in each of the cells through a high-speed data network. The operating voltage of the onboard electrical network is 317 V, the battery capacity is 51 kWh. Of course, ER can use excess energy during inertia and braking.

The original Porsche 911 six-speed clutch transmission has retained its place in the ER drivetrain, but that unnecessary ballast will soon be removed. Since electric motors provide maximum torque (up to 650 Nm when starting off), an electric sports car does not need any gears or a friction clutch - a simple and efficient manual transmission is enough.


Of course, the technological features of the prototype are not limited to this. The UQM electric motor used so far in the field of light commercial vehicles has a relatively low maximum speed of 5000 rpm for an electric machine and has efficient liquid cooling. On the other hand, battery packs do not have such a system - a rather surprising fact against the backdrop of the well-known problems of lithium-ion cells, the intermittent thermal regime of which often leads to a reduction in service life and even their premature failure.

Obviously, however, Rufus is not bothered by this. “We have experience operating the ER in an outdoor temperature of 38 degrees, and we are convinced that an electronically controlled battery system can solve this problem,” says Alois Rufus confidently.

How about a circle?

At the same time, the head of the company directly emphasizes that at the moment the electric car is only a prototype. The next evolutionary step in its development will be the installation of a high-speed electric motor specifically designed for the ER drivetrain and an advanced battery system with significantly less weight. Currently, the black sports model with power supply weighs 1910 kilograms, which, according to its creators, is at least 300 kilograms more than desired. However, the ER already achieves a 0 to 100 km/h acceleration time in less than seven seconds, its top speed reaches 225 km/h, and with a restrained driving style, a range of up to 300 km is possible with a single battery charge. The data is undoubtedly impressive and does not rule out a direct comparison with the Tesla Roadster that is already ready for mass production. At the same time, Alois Ruf cannot boast of such investment potential behind him, and it took only a year to bring the Ruf ER Model A to its current state.

In fact, the prototype is quite enjoyable to manage even in its awkward and imperfect form. The sound of an electric powertrain is far from being a sports car and is currently a muffled mixture of strange buzzing, humming and whooshing. However, pressing the accelerator pedal results in lightning-fast and even fast acceleration typical of electric motors, which will undoubtedly spark curiosity and an appetite for something more in many potential customers. Overweight and distribution issues have also disrupted the typical 911's aggressive cornering behavior, creating another problem that the Rufa team will have to tackle before the first limited-edition ER hits the market later next year.

text: Alexander Bloch

a photo: Ahim Hartman

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