Mercedes-Benz C-Class 2014 Review

A diesel for just $1500 more than the asking price of the petrol C 250 ($68,900)? That sort of premium could be recovered at the pump within a couple of years, but into year three could the C 250 BlueTEC owner continue to live with the added noise and vibration? We matched up the two cars to see.

Let's be clear, the C 250 BlueTEC was not an especially noisy car by the standards of four-cylinder diesels. Once the engine was warmed up it was acceptably quiet, and would purr gently at low revs.

More refined than the diesel, the petrol engine delivered plenty of torque across a wide band of revs, and it would rev quickly to the redline, but it wasn't a classically melodic engine higher in the rev range. There was a bit of turbo whine just near the limits of audibility when the engine was working harder, but Benz engineers have damped drivetrain-related NVH very well in most circumstances. Up to 100km/h tyre noise was subdued but prevalent in both cars. And rustle from the wind over the body became increasingly audible at open-road speeds.

Fuel consumption for the petrol model finished the week at 10.6L/100km, thanks to some extra freeway kilometres and the idle stop-start system. Restarting was very fast and silky, plus the engine could be kept running at red lights by holding the foot tensed lightly on the brake pedal, allowing an extra fraction of a second for fast starts. The BlueTEC engine also restarted quickly, albeit without the petrol engine's smoothness.

Fuel consumption in the C 250 BlueTEC was 7.9L/100km for the week, which was fine but unexceptional during the quieter school-holiday period.

Just like the petrol C-Class, the diesel's infotainment system could call up a fuel consumption bar chart that updated at 60-second intervals. It was telling that the fuel use never rose as high as 20.0L/100km, even motoring away from a cold start, and the fuel consumption fell rapidly as the engine temperature rose.

Both engines drove to the rear wheels through MB's seven-speed automatic transmission, a fine unit delivering seamlessly smooth shifting. There was an occasional conflict when in Sport+ mode, as an example, using the shift paddles and having the transmission kick-down in response to heavy throttle use.

Kick-down is there for emergencies – even when the driver is shifting sequentially. Nevertheless, I don't want it holding a lower gear from kick-down after I've shifted up using the paddles. What the driver wants, the driver should get...

Which leads to the Driver Assistance package, including Steer Assist. It can be unnerving, watching the C 250 steer itself through freeway bends. But it certainly works; it's a pity though that the car can't be left to its own devices for more than a few seconds at a time. At least it's the first step in autonomous driving – and as much as we can expect while car companies and governments around the world iron out legislation to allow self-driving cars.

At start-up, the petrol C 250, which was optioned with Airmatic suspension, defaulted to the Comfort setting. This provided softer ride and lighter steering with some feedback, but set to Sport mode the Mercedes rode nearly as well, with better body control in corners and stronger feedback through the wheel.

The Airmatic-equipped C 250 registered a marked improvement in handling, measured against certain Benz models from the recent past. Get the braking out of the way ahead of the turn-in point and the C 250 would nose right in to the inside line. Front-end grip was impressive and the Benz was very composed.

The BlueTEC version, riding on standard suspension, achieved similar levels of roadholding and handling, but without quite the same level of poise, as we've previously reported.

Holding the driver in place at higher cornering speeds, the driver's seat in the petrol C 250 proved firm but supportive. Despite the high range of adjustment available, the seat could be quickly set to suit drivers of most physiques, and provide a high level of comfort. A seat comfort option costing $1290 was specified for the C 250 BlueTEC.

Rear-seat accommodation was marginal in both cars, with the sunroof fitted. There was enough kneeroom for adults of average height, but headroom was light on. Tucking toes under the front seat still left a shortage of room to spread out with a taller driver in front.

Interior design was based on known Benz ergonomics, but embraced a new touchpad sitting above the traditional Comand single-point controller. There were 'back', 'favourite' and 'menu' buttons to bring up different options on screen. Swiping a finger from left to right or vice versa over the touchpad skipped forward or backward to the next music track, for instance. There were different displays available in the infotainment screen, one of which brought up the fuel consumption bar chart previously mentioned.

While Benz's new design is ergonomically different, it's not difficult to learn. The C-Class 'Human-Machine Interface' actually encouraged trial and error to determine how each function worked; being interesting and technologically modern it whets the user's curiosity.

Unfortunately, the infotainment display was not a touch screen – but looked like one. On the screen for the consumption chart mentioned above, there's a 'back' icon presented on the screen in the lower left corner. It's there to inform the user that it's not possible to drill down any further – and the only way is back. The problem however, is it looks like it can be actuated by touching the screen. It can't.

The gear selector is Benz's now commonplace column-mounted unit, which is easy enough to use, but still feels 'wrong' in a car of the C 250's size. There's an engine start button on the dash behind the wheel on the right, and the handbrake is actuated by pushing a toggle and is released by pulling the same toggle located on the lower dash fascia where the handbrake release has been situated for years. Switchgear for electric windows, mirrors and seat adjustment are all located on the door, following the paradigm of earlier Benzes.

Both cars impressed with their elegance and all-round competence during the week in our possession. And which one to buy? I would spend the $1500 just for the convenience of going those few extra days without needing to refill.