The Mercedes-Benz C-class, the lowest-end Mercedes-Benz sold in the U.S., underwent an upgrade in 2008 that modernized the car considerably, making it an excellent value in a semi-sporty small luxury sedan. We earlier reviewed, and praised, the C300 Sport and the C63 AMG. This is the first time we've seen the 2010 Mercedes-Benz C350.
But the C350 sent to us turned out to be an example of how not to option up a C-class. First of all, the need for the car's 3.5-liter V-6 seemed questionable, as the 3-liter V-6 in the C300 does a perfectly good job. Second, our car lacked the navigation system option, saddling it with what is probably the worst iPod integration we've seen. The car was equipped with an 18-inch AMG wheel package, money which could have been much better spent making the cabin electronics useful.
C350 versus C300
According to Mercedes-Benz specifications, the C350 gets you to 60 mph in 6.1 seconds, exactly 1 second faster than the C300. The 3.5-liter V-6 in the C350 produces 268 horsepower and 258 pound-feet of torque compared with the C300's 228 horsepower and 221 pound-feet of torque.

Obviously, the C350 goes faster than the C300, but not by much. The sensation of acceleration is even less different, as the only transmission available for the C350 is a seven-speed automatic. Although Mercedes-Benz has done an excellent job of refining automatic transmissions to give a near-manual transmission feel, it still masks the engine performance behind torque converter softness.
The C300 can be had with that seven-speed automatic or a six-speed manual, the latter being more of a driving enthusiast's choice. In the C350, a button near the shifter toggles the mapping between Comfort and Sport settings, making the gear changes more aggressive. You can also manually change gears by moving the shifter from side-to-side, producing reasonably quick shifts. But we didn't find a huge performance gap between the C300 and C350.

Both C-class models use the same suspension, a four-wheel independent setup with stabilizer bars front and rear along with antidive control. In either model, it does a wonderful job of keeping the car composed during hard cornering. The 37 extra pound-feet of torque should make a difference accelerating out of a turn, but we didn't feel the C350 had a substantial edge.
As you would expect, the C350 does take a fuel economy hit for its larger displacement, but it's only 1 mpg, with EPA ratings at 17 mpg city and 25 mpg highway. We achieved an average of 20.1 mpg during mixed city and freeway driving, and observed trip computer mileage over 24 mpg during long freeway trips.