Apparatus and method for reducing overall weight of rear differential cooling system

A body panel system for a motor vehicle, comprising:

• a rear diffuser including a first air inlet and a second air inlet;
• an underbody panel overlying said rear diffuser;
• a first air tunnel formed between said rear diffuser and said underbody panel, said first air tunnel extending from said first air inlet to a first air tunnel outlet above said rear diffuser;
• a second air tunnel formed between said rear diffuser and said underbody panel, said second air tunnel extending from said second air inlet to a second air tunnel outlet above said rear diffuser;
• a rear valance including a first vent opening and a second vent opening discharging air received from said first air tunnel and said second air tunnel;
• and
• a heat exchanger providing cooling to a rear differential of said motor vehicle wherein said heat exchanger is provided between (a) said first vent opening and said second vent opening and (b) said first air tunnel outlet and said second air tunnel outlet.