They're typically side by side. Generally in-wheel systems are expensive, because they're harder to manufacture and of course the flywheel system should be susp

They're typically side by side. Generally in-wheel systems are expensive, because they're harder to manufacture and of course the flywheel system should be suspended, so you have to fit a suspension system in there as well. Space isn't at a premium in cars, and on motorscooters and motorcycles they just use a high rpm engine (10000 rpm in typical operation) to have smoother torque output.