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Mercedes-Benz S300 Hybrid Road Test

  • Until the Plug-in arrives S300 Hybrid cleanest S-Class in the range
  • 115g/km and 64mpg promised
  • Will cost users around £325 a month in tax.

If you can afford a car as grand as the Mercedes S-Class, you’d think saving money wouldn’t be much of a problem. Of course, that doesn’t mean you don’t want to save the planet, and so Mercedes has the answer in the form of its S-Class Hybrid models.

The forthcoming S-Class Plug-in hybrid is due to be unveiled at Frankfurt later this year, but we can tell you this car will achieve less than 75g/km of CO2 output. Not only does that mean it’ll be London Congestion Charge exempt, but it’s also cleaner than a Toyota Prius, Honda Insight and the Lexus CT200h.

For now though we’ll have to make do with the S300 Hybrid, which doesn’t plug into your wall socket, but does use a 2.1-litre four-cylinder diesel teamed with a small electric motor to keep economy up and emissions down. The result is 115g/km and 64mpg on the combined cycle, which still betters the Honda CR-Z or more conceptually similar Lexus LS600h with 199g/km and 32.8 average mpg.

Mercedes S300 hybrid badge

Considering the S-Class is over 5.1 metres long, that’s an impressive pair of numbers right there. Of course the diesel-only S350 CDI manages a credible 51mpg and 146g/km without electric assistance and will costs around £2,000 less when the Hybrid goes on sale in 2014 – it’s no surprise it’s this diesel model that will take the lion’s share (around 90 percent) of the UK market.

But where emissions really matter – in the company car market for example – this Hybrid makes a lot of sense.

Of course, it can’t quite match the refinement of the 3.0-litre V6 diesel, the slightest of four-cylinder diesel rattles making its way into the cabin at lower speeds. Increase the rate of travel and the noise subsides slightly, and the S300 Hybrid is as a relaxed and refined cruiser as the rest of the range.

But unlike the Porsche Panamera S E-Hybrid the electric motor in the Mercedes is tiny - offering only 27bhp – and as such it barely seems to provide any assistance in the real world. Certainly you’ll need a ballet-light right foot to maintain any form of electric propulsion, as anything above a crawl sees the diesel engine fire back in.

Mercedes S300 engine

It’s not entirely imperceptible either, though this may be down to the noise as much as anything else. At least performance is acceptable, completing the benchmark 0-62mph sprint in 7.6 seconds, and as long as you’re not in a desperate hurry it rarely feels ponderous.

Like every other S-Class in the range the S300 Hybrid boasts a fantastic interior, fitted with multi-adjustable and extremely comfortable seats – especially where the option boxes are ticked to cool, heat and massage the occupants sat upon them.

The dashboard has been thoroughly reworked as well, with a flowing and fluid design interspersed with only the odd familiar piece of switchgear. At the dashboard’s heart are a pair of 12.3inch TFT screens, one used to display primary drive functions - speedometer, rev counter etc - and the other for secondary devices such as the sat-nav, audio and climate controls. They're both controlled by the Comand controller in the centre console.

Mercedes S300 hybrid instruments

They look better than ever too, with crisp, smooth graphics and a high definition display when switching to the reversing camera or night vision screen. We’re still not entirely convinced the one in front of the driver is any better than traditional instruments, but appreciate the extra functionality it affords.

All of this comes at a cost, though, and company car users lucky enough find the S300 Hybrid on their lists when it arrives in the UK early in 2014, will pay around £325 a month in tax for the privilege. That may sound a lot, but the Audi A8 2.0 TFSi Hybrid will cost 40 percent tax payers £430 monthly and the BMW ActiveHybrid 7 £506.

In the face of numbers like that, the new S300 Hybrid seems something of a bargain. Sure the regular S350CDI is the better car, but you’ll pay £500 a month in company car tax – so the Hybrid represents a significant £175 a month saving. And you don’t get to be in a position of driving a Mercedes S-Class without knowing that at the end of the day, money talks.

Read the full Parkers Mercedes S-Class review here

Also Consider

Audi A8

The Audi A8 2.0TFSi Hybrid uses a petrol engine and an electric motor to achieve its impressive 147g/km CO2 emissions and 44mpg economy but not only does it cost more to tax but it’s not as comfortable as the Mercedes.

Porsche Panamera

If you’re keen to get behind the wheel rather than onto the rear bench the Panamera S E-Hybrid is the car for you. Although it’s substantially more expensive it’s also far more efficient and economical than its Mercedes counterpart.

Lexus LS

Arguably the original luxury executive hybrid car, the Lexus LS600h is already feeling its age, despite a relatively recent refresh – and though comfortable it just can’t compete with the Mercedes for efficiency, driver appeal or image.