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Mercedes-Benz C320 CDI/C350

Mercedes-Benz

Review

Two cracking new engines – one petrol and one diesel – give a high-power boost to the already legendary Mercedes-Benz C-class range. Ben Whitworth is suitably impressed by both models

DON’T be fooled. They may look like every other C-class model you pass on your way to work, but Mercedes-Benz has given its compact executive range a major pick-me-up. Well, two actually. In come two new V6 flagship powerplants, the 320 CDI and 350 petrol, which replace the old 270 CDI diesel and 320 petrol engines. More power and more refinement, without, Mercedes claims, any major price hike. The saloon, estate and hatch all go on sale in July.

We are already familiar with the new petrol V6 – it made its debut last year in the brilliant new SLK roadster, but this is the 320 CDI’s debut. It’s the first in a family of advanced modular engines that will eventually spin off V8 and V12 turbodiesels, and it packs a full technological punch.

The turbodiesel is hugely advanced and features a third-generation common rail injection system with piezo-electric injectors, an aluminium-crank, a 24-valve head and electrically-adjusted turbocharger vanes. Fuel is stored at an unfeasibly high 1,600bar – high enough to cut through 5mm steel plate, Mercedes rather bizarrely claims – and the engine is clean enough to meet Euro IV-emission levels without a particulate trap.

The new 320 CDI – ignore the badge, it’s actually a 3.0-litre engine – develops 221bhp at 4,000rpm and a chunky 306lb ft of torque at a low 1,400rpm. Opt for the beefier seven-cog 7G-Tronic automatic gearbox – around £1,100 more than the standard (and now very good), six-speed manual – and torque will climb to 376lb ft at 1,600rpm. That’s 32% more power and 27% more torque than the outgoing 270CDI.

On-paper, performance figures are impressive. Fitted with the 7G-Tronic transmission, the C320 CDI will bullet to 62mph in 6.9 seconds (8.1 seconds in six-speed manual guise) before being electronically reined in at 150mph.

Despite this dramatic performance hike, combined cycle fuel economy has dropped only slightly, from 41.5mpg for the outgoing C270 CDI to a still impressive 37.7mpg for the C320 CDI. There’s no word yet on CO2 levels, but expect the engine to match, if not better, the old 270 CDI’s figure of 181g/km.

The V6 petrol is the same 3,498cc engine found in the new SLK, developing the same hefty 268bhp at 5,750rpm, and driving the rear wheels through either a six-speed manual or optional seven-speed automatic. It’s also a terrifically quick car – sprinting to 62mph in 6.4 seconds – and 258lb ft of peak torque arrives at a low 2500rpm, promising good acceleration through the rev range. For such a muscular powerplant, the V6 is surprisingly frugal, returning 29.6mpg on the combined cycle. Later on this year, the V6 petrol will be detuned to 231bhp and rebadged C280 to replace the current C240, and although yet to be confirmed, a less powerful version of the V6 diesel will arrive to bridge the gap between the C220 CDI and the flagship C320 CDI. As expected, these engines will also be used throughout the Mercedes line-up, finding their way into the E, S, M, CLK and CLS.

The arrival of these two engines also heralds the debut of the Sport model, which will join the existing Classic, Elegance and Avantgarde range. It adds bigger wheels, stiffer suspension, a more aggressive body kit and a host of other desirables, all for £1,830 over the standard car. The rest of the C-class package remains unchanged. That means sleek but sober sheetmetal, a cabin that finally feels worthy of the Mercedes-Benz badge, higher overall safety and luxuries levels, wallet-friendly running costs and strong residuals.

While both engines put a real spring in the step of the C-class, Mercedes-Benz dealers will have some serious work on their hands – the imminent arrival of the new BMW 3-series as well as last year’s heavily-revised Audi A4 will mean upper-echelon user-choosers will have a wide and appealing range of small German executives from which to choose. The firm believes the new diesel engine will significantly boost UK diesel sales, bringing them up from 47% in 2005 to 50% of total C-class sales this year, which should hit 26,000. That said, the C320 CDI is unlikely to be a huge seller, accounting for around 1,300 sales this year – just 5% of total sales.

Behind the wheel
THE diesel first. This engine is a real gem. Sweet, rev-happy and cultured, it provides plenty of power to effortlessly bullet the C-class along at points-gathering speed. Pulling away is excellent, with little if any discernible lag, making busy junctions a cinch.

This car feels hot-hatch quick off the line, and acceleration at all speeds is relentless. Throttle response is particularly sharp for a diesel – squeeze the accelerator and the car leaps forward with an addictive slug of power, revving cleanly through to its 4,200rpm redline. There seems to be little correlation between engine revs and road speed, particularly when wafting along in seventh gear when the engine is humming along quietly at 1,700rpm at the national speed limit. For the most part the engine is all but silent – it’s only on start-up and at parking speeds that the thrummy exhaust note pervades the cabin.

It’s the kind of car that can waft you quickly and effortlessly from Edinburgh to London non-stop, and leave you fresh and relaxed on arrival. A mini GT, if you like, with performance and refinement, if not the style, to match.

After the superlative diesel, the new C350 petrol is somewhat of a ho-hum drive. Sure, it pulls well, ripping through to its redline with real venom. And yes, it sounds great – pedestrians get the full serrated wail as the car slips through the gears, but drivers will feel short-changed because in the cabin, the engine and exhaust note is hushed and muted.

But, and it’s a big one, despite its prodigious power and zingy exhaust note the C350 just doesn’t have the kind of tail-up enthusiasm and deep-seated driver appeal you’d expect of a 268bhp sporting saloon.

You can have fun if you push hard enough, but the Mercedes seems to tolerate rather than enjoy any gung-ho actions. A BMW 330i would have it licked.

Instead, the C350 feels every bit like a scaled-down S-class: refined, smooth and a wonderfully relaxing companion on a long drive, no matter what the road or weather conditions.

Which is no bad thing of course, if you want an effortless motorway cruiser rather than an A-road grin-inducer. Both cars ride and handle with the kind of well-damped suppleness and finesse that their Audi, Lexus and Jaguar rivals cannot match. No matter how pitted the road or how aggressively cornered, the C-class always feels poised and confident.

Driving verdict
DRIVE both cars back to back, and there’s arguably no reason why you would take the petrol over the diesel, even if economy and tax benefits weren’t on your list of priorities. Fitted with the seven-speed automatic, the 320 CDI feels every bit as quick as the petrol off the line, and delivers a massive mid-range punch that the petrol simply cannot better.

And don’t forget the diesel’s economy advantage – no matter how hard it’s driven, the C320 CDI is always going to make the C350 look thirsty.

With such a fine engine in its C-class line-up, it’s little wonder Mercedes-Benz reckons diesel sales will be on a par with those of petrol this year.

C320 CDI fact file

Engine: 2,987cc
Max power (bhp/rpm): 221/4000
Max torque (lb-ft/rpm): 306/1,400 (manual) 376/1600 (auto)
Max speed (mph): 150mph (limited)
0-62mph (secs): 8.1 (manual) 6.9 (auto)
Fuel consumption (mpg): 37.7
CO2 emissions (g/km): TBA
Fuel tanks capacity (l/gal): 70/15.4
Service intervals (miles): variable
On sale: July
Price (OTR): £26,000 - £28,500 (est)

C350 fact file

Engine: 3,498cc
Max power (bhp/rpm): 268/5750
Max torque (lb-ft/rpm): 258/2500
Max speed (mph): 155 (limited)
0-62mph (secs): 6.4 (manual and auto)
Fuel consumption (mpg): 29.6
CO2 emissions (g/km): TBA
Fuel tanks capacity (l/gal): 70/15.4
Service intervals (miles): Variable
On sale: July
Price (OTR): £30,000 - £32,500 (est)

CO2 emissions and fuel consumption data correct at time of writing. The latest figures are available in the Fleet News fuel cost calculator and the company car tax calculator.

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