From my post back in June:

Width: Mostly 45", except 38" where the wheel well intrudes.

Height: 32-33" in the rear, decreases to 27" above the folded-down rear seat.

Depth (Rear Seat Up): 37" deep at the floor, 23" from top of seatback to door.

Depth (Rear Seat Down): 64" to top of back seat (down), 68" to back of front seat (my position, YMMV).

So, the X3 might be 3 inches shorter than the 528, but depending on how it was measured - either two inches wider or 5 inches narrower. I am 5'11 - My 5'8" wife moves the seat forward about an inch (69" deep).