Where can you stow your baggage so that you do not increase your fuel consumption unnecessarily?

Your selected answer is correct. Stowing your baggage in the boot (trunk) and behind the front seats helps maintain better aerodynamics and weight distribution, which can lead to more efficient fuel consumption. According to German traffic regulations, it is important to secure your luggage properly to avoid it becoming a hazard in the event of sudden stops or accidents.

Storing items on the roof-rack can adversely affect your vehicle's aerodynamics and increase fuel consumption, as well as potentially pose safety risks if not secured properly. Thus, the combination of storing items in the boot and behind the front seats is the most fuel-efficient and safest choice under German traffic rules.