[jyl]

So, deck is not deep enough for garage, will need to use the basement in addition to, or instead of, the under-deck area. Unless you do the shed roof extending from edge of deck, but may not be enough height.

Should build garage long enough for the biggest SUV plus plenty extra for clearance, cabinets and whatever - think resale value. A Suburban is appx 220" long. A 911SC is appx 170" long.

Under deck is tall enough, 81", for a big SUV as long as no roof box - not much room to spare by the time you think header, door, lighting, and roof rack on the SUV - but should work. Not tall enough for a lift, but sounds like that is ok w/ you. Is there more, or less, headroom in the basement?

I assume each of the two "bays" under the deck is 114" wide, so both together are plenty wide enough for a two car garage.

Say, why is the finished/inhabited portion of the house raised 8' off the back yard grade? Is is a flood thing, does the lot slope, or what?