Utility
Neither the Mercury Sable nor the Toyota Avalon has a marked advantage when it comes to seating capacity.
Dimensions
The Toyota Avalon's tank is almost the same size as the Sable's, though the Mercury Sable's is slightly larger.
The Toyota and the Mercury Sable compete for the same parking spaces.
Convenience
The Toyota Avalon's fuel tank will need to be replenished slightly more often than the unit in the Mercury Sable.
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 Toyota Avalon to the dealership as the Mercury Sable.
With respect to gas mileage, the Toyota Avalon is a tad better than the Mercury Sable, but not by much.
The Avalon won't tax your gas budget substantially more than the Mercury Sable will.
In terms of MSRP, the Mercury Sable doesn't cost much less than the Toyota Avalon.
Handling
With their comparable turning radii, the Toyota and the Sable quite certainly handle almost the same into and out of tight spots.
Comfort
While the front cabin in the Mercury Sable offers a bit more head room than the Toyota, there really isn't much of a difference.
While the rear of the Mercury Sable offers a bit more head- and leg-room than the Avalon, there honestly isn't much of a difference.
Warranty
The Toyota Avalon and the Mercury have the same basic warranty.