Am confused as well. Is your garage floor a slab on grade or is there a floor structure with open space below? If it is a floor structure it would have to be concrete on metal pan over metal bar joists or some type of concrete beam structure. If the floor is a slab on grade and the grade is just below slab level then simple slab edge turndowns should suffice. I would recommend that if the floor is slab on grade that you thicken the slab at the car wheelbase for additional support. If you find out what is going on in your drawing please post to let us know. Good luck!

Slab on grade with concrete beams, see attached. No open space below.

The footing depth under the livable portion of house looks to be too short for a basement, but tall enough for a high crawlspace, maybe for HVAC equipment (not sure why a full basement wouldn't be dug). The garage footings look to only go down to frost depth. The drawing is also confusing as it looks to show the footing steps behind that connect to the Laundry Room footings.