Mercedes-Benz C 180 Bluetec review

The new Mercedes-Benz C-class has brought engine downsizing to the compact executive saloon class, with Mercedes choosing a small 1.6-litre, four-cylinder engine for its entry-level diesel offering.

Actually, there are two versions of this same engine. One is the C 200 Bluetec with 134bhp and the other is this C 180 Bluetec, with a mere 114bhp. As is the case with the smaller diesels in the A-Class range, the engines (and gearboxes, in the case of the manual versions) are sourced from Renault, and here we find the familiar 1.6 dCi.

According to Mercedes, the engine has been modified in exterior detail, allowing it to rotate 90 degrees from its transverse positioning in Renault/Nissan models, to fit into the C-Class’s longitudinal layout.

Furthermore, the software that runs the engine has been changed to alter its character towards a more Mercedes-like attitude. The aim was to achieve a stronger, smoother torque delivery and reduce noise and vibration, while keeping fuel economy high.

Official performance and economy figures are encouraging, the C 180 Bluetec achieving 67mpg on the combined cycle and reaching 62mph from rest in 11.1sec when mated to a six-speed manual gearbox. There’s also the option of a seven-speed automatic transmission. While the power output is lower than the usual application of this engine in Renault/Nissan models, the torque figure is up, from 151lb ft to 206lb ft. This becomes quite obvious once you start driving it.

Pretty refined. On start-up and at idle, there are no serious hints of what kind of fuel is being burnt up front. There's no real clatter and few vibrations get through to the driver, proving that Mercedes has worked hard on soundproofing materials.

The manual gearbox is pleasant to use, with a light action and fairly precise shift. The engine feels willing, but it's not really in the same league as the 2.1-litre unit in the C 220 Bluetec for pace, making the car feel slower than it should. At low revs there's a bit of a flat spot – but maximum torque is available from as low as 1500rpm, so as long as you keep it spinning in its sweet spot, you'll be able to keep up with other traffic without too much trouble.

There are five different driving modes, offering the driver the choice between Eco, Comfort, Sport, Sport+ and Individual. In each position, four parameters are changed, namely the throttle response, steering effort, air conditioning power and start-stop system. In automatic models, the shift points are tailored to each mode too. In Sport and Sport+ modes, the engine management matches the revs with each downshift, an entertaining – if somewhat pointless – feature on such a frugal, economy-minded diesel.

The limiter cuts in at at 5200rpm, but you'll rarely want to push it that hard, as there are no real gains in peformance at high revs and refinement suffers as the engine strains at these higher speeds. We reached 47mpg in city driving, a bit far from the official figure, but a light-footed approach would soon see that figure rise towards 60mpg.

On the motorway where these cars spend most of their time, the 114bhp engine starts to show its limitations. At higher speeds it needs to work harder and becomes more intrusive, and overtaking moves need to be planned quite far in advance, unlike in the punchier large-capacity diesels in the range.