Utility
The Mountaineer is a better choice than the Jeep Commander with respect to transporting cargo, especially if you often need to carry a lot of cargo or massive pets.
The Mercury Mountaineer and the Jeep Commander can accommodate the same number of passengers.
Performance
The Jeep Commander is likely to feel a little slow because of its high horsepower-to-weight ratio.
Dimensions
The Jeep Commander is a bit heavier than the Mountaineer.
The Jeep Commander's tank is approximately the same size as the Mercury Mountaineer's, though the Mercury Mountaineer's is somewhat more capacious.
The Jeep Commander and the Mercury Mountaineer compete for the same parking spaces.
Convenience
You'll most definitely take the Jeep Commander for a fill-up about as often as the Mercury Mountaineer.
Cost
The destination charge is a standard charge for transporting the vehicle from its point of origin to the dealer. It costs roughly the same to get the Mercury Mountaineer to the dealership as the Jeep Commander.
As far as gas mileage, the Mercury Mountaineer is slightly better than the Jeep Commander, but not by much.
Regarding MSRP, the Jeep costs roughly as much as the Mercury Mountaineer (though the Mercury Mountaineer is a bit cheaper).
Drivetrain
The Jeep Commander's engine isn't much more massive than the Mercury Mountaineer's.
Comfort
Taller drivers will considerably enjoy the extra head room in the Commander's front cabin compared to the Mercury.
The Jeep Commander is not particularly roomier for your passengers than the Mercury Mountaineer.
Overview
The Jeep Commander and the Mercury Mountaineer have the same basic warranty.