The motor is directly connected to the rear wheel, there is no freewheel (or clutch) inbetween. This would be like a manual car when you coast, the motor slowly reduces it's RPM as the road speed drops. What this also gives you is the possibility to use the motor as a brake, in other words regen braking. The Q140MD has a dedicated thumb-lever for regen which works really quite well.
So, after coasting, when you get on the throttle again you start feeding the motor power and it will begin producing torque, slowly starting to accellerate you again. No "speed up" needed.*
The only freewheel on this bike is between the motor and the pedals, which means the pedals don't always have to rotate at the same speed as the motor.
*As a side note, this is one of the things that are different between a speed controlled throttle (as seen in ECO mode) and a torque controlled throttle. Torque control functions as I described above, but speed control tries to map a given amount of twist (for the sake of argument, say 10 degrees) to a given speed (say 10mph). If you are coasting at 20mph, in ECO mode, and apply 10 degrees of throttle twist, you are "requesting" 10mph from the bike. It will then actively slow you down to 10mph by applying regen braking before it applies torque to keep you at that speed.
Torque control on the other hand maps a given amount of throttle twist to a given amount of torque (in reality I believe this is controlling amperage, but amperage more or less equeals torque in an electric motor). So say you are coasting at 20mph, and you apply 10 degrees of twist. This gives you a small amount of additional torque from the acelleration. Now depending on if you are going uphill or downhill that may or may not be enough to result in accelleration, but the controller doesn't care as it is giving you the torque you have requested. This is exactly like you would expect from a petrol engined car or motorbike.