Handling
The HUMMER H3 and the CX-9 have approximately similar tires.
With their comparable turning circles, the HUMMER H3 and the Mazda CX-9 doubtless handle roughly the same into and out of tight spots.
Drivetrain
The Mazda CX-9 and the HUMMER H3 have similar-sized engines, with a slight advantage to the HUMMER H3.
Utility
Drivers with frequent child-duty might favor the Mazda CX-9 over the HUMMER H3.
The Mazda CX-9 is a better choice than the H3 in terms of hauling capacity, especially if you frequently need to carry a lot of cargo or big pets.
The HUMMER H3 outpulls the Mazda CX-9 by a massive margin.
Comfort
While the front cabin in the H3 offers a bit more head room than the CX-9, there really isn't much of a difference.
The Mazda offers more head- and leg-room to your passengers than the H3 does.
Dimensions
The HUMMER H3 is a little more ponderous than the Mazda CX-9.
Your wallet will hurt more every time you fill up the HUMMER than the Mazda CX-9 because of its more capacious tank.
The HUMMER H3 and the Mazda CX-9 compete for the same parking spaces.
Cost
The destination charge is a standard charge for transporting the vehicle from its point of origin to the dealer. It costs about the same to get the HUMMER to the dealership as the Mazda CX-9.
The Mazda CX-9 isn't much more expensive than the HUMMER H3 in terms of MSRP.
Overview
The basic warranty that comes with the Mazda CX-9 isn't quite as generous as the HUMMER H3's.