Utility
The Mazda MAZDA6 is likely a better choice than the Mitsubishi when it comes to hauling capacity, especially if you frequently need to carry a lot of stuff or pets.
The Mazda MAZDA6 will quite certainly prove more convenient than the Mitsubishi Eclipse for those of you with frequent kid-cargo.
Performance
As far as horsepower, the Mazda packs quite a wallop and will knock the Mitsubishi Eclipse down a few rungs. On the other hand, note that high horsepower engines often command higher insurance premiums.
Dimensions
The Mitsubishi's tank is approximately the same size as the MAZDA6's, though the MAZDA6's is a tad more capacious.
The Mitsubishi rides lower than the Mazda MAZDA6, which is a good thing for its center of gravity and ease of access.
The Mitsubishi Eclipse and the Mazda MAZDA6 compete for the same parking spaces.
Convenience
You quite certainly won't have to visit your friendly gas station more often with the Mazda MAZDA6 than with the Mitsubishi, because both offer comparable ranges.
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 Mazda MAZDA6 to the dealership as the Mitsubishi Eclipse.
In terms of fuel economy, the Mitsubishi Eclipse bests the Mazda.
There isn't much of a difference in gas mileage here, but if you must know, the Mitsubishi is slightly more economical than the Mazda MAZDA6.
With respect to MSRP, the Mitsubishi Eclipse doesn't cost much less than the Mazda MAZDA6.
Handling
The Mitsubishi Eclipse and the Mazda MAZDA6 have approximately comparable tires.
With their comparable turning circles, the Mazda MAZDA6 and the Mitsubishi likely handle roughly the same into and out of tight spots.
Drivetrain
The Mitsubishi's engine is markedly smaller than the MAZDA6's. Keep in mind that a smaller engine usually has to work a little harder; on the flip side, smaller engines are often cheaper to fix.
Torque is the force that lets you accelerate quickly, and in this respect, the MAZDA6 is significantly more powerful than the Mitsubishi Eclipse.
Torque equals pickup, and the MAZDA6 will have picked up and gone by the time the Mitsubishi finally gets moving.
Comfort
Taller drivers will considerably enjoy the extra head room in the MAZDA6's front cabin compared to the Mitsubishi Eclipse.
The Mazda MAZDA6 provides more head- and leg-room to your passengers than the Mitsubishi Eclipse does.
Overview
The basic after-sale protection that comes with the MAZDA6 isn't quite as generous as the Mitsubishi Eclipse's.