Audi A1 e-tron Extended Range Urban EV Uses Wankel Engine

Like so many manufacturers these days, Audi is developing electric powered cars. This includes the Audi e-tron supercar based on the Audi R8. At the other end of the scale, there is the Audi A1 e-tron for urban duty. Like the Chevrolet Volt, this two-door, four-passenger A1 e-tron is an extended range electric vehicle.

Audi uses a small single-rotor Wankel engine in this extended range electric vehicle (EREV). The small single-rotor, 254 cc rotary engine operates at a constant 5,000 rpm for optimum fuel efficiency. A Wankel engine was chosen because it is lightweight and operates virtually silently and vibration-free. The transversely mounted engine is placed low at the front of the car for a low center of gravity. Power electronics are mounted above the electric motor. The T-shaped battery pack is located below the floor.

The A1 e-tron can travel up to 31 miles (50 kilometers) on its 12 kilowatt-hour battery pack. After that, he Wankel engine starts up to drive a 15 kilowatt generator that charges the 380 volt, 96 prismatic lithium-ion battery. The extra 124 mile (200 kilometer) range, which is intended primarily for interurban driving, uses the 3.17 gallons (12 liter) fuel tank. Audi says this translates to an overall 123.80 mpg (1.9 L/100 km) and CO2 emissions of 72 g/mile (45 g/km).

Electric energy is supplied to a synchronous electric motor driving the front wheels through a single-speed transmission. The motor has a peak rating of 102 horsepower (75 kilowatts) that’s available for short bursts and a continuous rating of 61 horsepower (45 kilowatts). The Audi A1 e-tron has a top speed of 81 mph (130 km/hr) and can accelerate to 0 to 62 mph (100 km/h) in 10.2 seconds.

A fully depleted battery can be recharged in approximately three hours from the 380 volt grid. The socket for the standard charging plug is behind the Audi rings in the grille. A display located by the plug-in connection shows the car’s current charge status and the charge time remaining.

Electro-mechanical power steering is used. Braking is accomplished via a hydraulic fixed-caliper brake on the front axle and two novel electrically-actuated floating-caliper brakes on the rear axle, plus regenerative braking that creates electricity to help recharge the batteries. The air conditioning compressor is electrically powered and a heat pump controls the temperature of the cabin and the battery. On-board electronics also integrate navigation data such as destination and route profiles to automatically activate the range extender as needed, providing the kind of seamless driving experience required as we transition to an advanced technology vehicle future.