Instead of a conventional starter, the smart fortwo mhd works with a start/stop generator that uses the engine's "idle phases" as efficiently as possible. The mhd switches the engine off as soon as you brake and fall below a speed of 8 km/h. When the traffic starts moving again, take your foot off the brake pedal and the engine will start again without delay so that you can continue your journey. The smart fortwo mhd's start/stop generator enables a fuel saving of up to 11% in city traffic, without compromising on performance or comfort. The mhd technology works perfectly with the automated manual 5-speed transmission: First gear is always automatically engaged when the engine restarts.