Utility
Neither the Mercury Mountaineer nor the Toyota Highlander has a marked advantage as far as seating capacity.
Towing is substantially more the Mercury Mountaineer's forte than it is the Toyota Highlander's.
Dimensions
The Mercury Mountaineer is substantially more bulky than the Toyota.
Your wallet will hurt more every time you fill up the Mercury than the Toyota Highlander because of its larger tank.
The Toyota and the Mercury Mountaineer compete for the same parking spaces.
Convenience
You most certainly won't have to visit your friendly gas station more often with the Toyota Highlander than with the Mountaineer, 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 almost the same to get the Highlander to the dealership as the Mercury Mountaineer.
The Highlander will save you money at the pump compared to the Mercury Mountaineer.
When it comes to fuel economy, the Toyota has the Mercury Mountaineer beat.
In terms of MSRP, the Mountaineer costs roughly as much as the Toyota Highlander (though the Toyota Highlander is somewhat cheaper).
Handling
With their similar turning radiuses, the Mountaineer and the Toyota Highlander likely handle roughly the same into and out of tight spots.
Drivetrain
The Toyota's engine is significantly smaller than the Mercury Mountaineer's. Note that a smaller engine usually has to work a little harder; on the flip side, smaller engines are often cheaper to fix.
The Toyota has no lessons to learn as far as pickup from the Mercury Mountaineer.
Comfort
While the front cabin in the Toyota offers a bit more head room than the Mercury Mountaineer, there frankly isn't much of a difference.
The ampler interior dimensions of the Toyota Highlander make it significantly roomier for your passengers than the Mercury.
Overview
The Toyota Highlander and the Mercury Mountaineer have the same basic warranty.