Cost
Producing an exact gas mileage evaluation is so tricky that some think not even the federal government can do it, but it looks as though both the ES 350 and the ES 350 perform about similarly in terms of gas mileage.
The ES 350 won't save you much money at the pump compared to the Mercedes-Benz C-Class.
With respect to MSRP, the Lexus doesn't cost much less than the Mercedes-Benz C-Class.
Utility
The Mercedes-Benz C-Class and the Lexus can accommodate the same number of passengers.
Convenience
You'll quite certainly have to take the Mercedes-Benz for a fill-up more often than the ES 350 because of its tank size and gas mileage.
Comfort
While the front cabin in the Lexus ES 350 offers a bit more head room than the Mercedes-Benz C-Class, there frankly isn't much of a difference.
The Lexus ES 350 provides more head- and leg-room to your passengers than the Mercedes-Benz C-Class does.
Dimensions
The C-Class's tank is about the same size as the Lexus ES 350's, though the Lexus ES 350's is a tad larger.
The Mercedes-Benz C-Class and the Lexus ES 350 compete for the same parking spaces.
Handling
With its tighter turning radius, the C-Class is quite certainly sprier than the Lexus ES 350, something to consider if you do a lot of city driving; however, note that a vehicle with a tight turning circle may feel a bit twitchy on the highway.
Drivetrain
The Lexus has no lessons to learn in terms of torque from the Mercedes-Benz C-Class.
Warranty
The Lexus and the C-Class have the same basic warranty.