While I liked how the PAD concept threw GMC back into one of it's historical segments (motorhome), I thought it was too extreme. So, I drew this up, thinking it could be a futuristic bus - should GM ever re-enter that market in the distant future...
I based the majority of the coach's shape off the old "Buffalo Bus" (PD4107, PD4108, P8M4108A, PD4903, PD4905, P8M4905A, H8H649), but attempted to integrate some PAD design cues into it.
I couldn't decide how to do the roof treatment, so I did two different designs, for two different operators. The Trailways coach features a transparent vista window that wraps down the side of the coach on the leading edge of the GM logo. The Greyhound bus simply takes the transparent roof to the rear of the coach, and is a little more conservative in overall form.
I'd say fuel cell power could propel the coach, but I'd also reason a Hybrid system, powered by the (Isuzu) Duramax 7.8L I-6, could be utilized as well.