2014 Mercedes-Benz S500 Plug-in Hybrid review

We already know that the 2014 Mercedes S-Class is a luxury car par excellence, but can it really do everything it normally does while using less fuel than a Toyota Prius?

It certainly has some impressive on-paper stats – 100.9mpg and CO2 emissions of just 65g/km, even if the £87,965 price causes you to wince. Still, it is subject to a low 5% rate for company car tax, and entry to the London Congestion Charge zone is free.

What's the 2014 Mercedes S500 Plug-in Hybrid like to drive?

Quiet. Very quiet. It's like a church. On the moon. You don't so much head for a destination as drift serenely through the scenery passing by your window.

The reason for this is the hybrid power system, which mates a twin-turbo 3.0-litre V6 engine with an electric motor mounted inside the automatic gearbox. There are numerous modes for your chauffeur to get the hang of – one gives all-electric power, another gives a hybrid mode which mixes petrol and electric oomph as the car sees fit, and another uses the petrol engine to save battery power.

In town, you'll most likely use electric power only (if you've plugged in the car to charge it up the night before), and this really shows off the car to its best. It's easily quick enough to keep up with the most bustling of rush-hour traffic and, of course, goes about its business silently. The only noise you hear is very slight road noise, and even then it's minimal.

Up the pace out of town and the V6 engine cuts in and out utterly unobtrusively. There's no vibration and only a faint V6 growl to let you know that fossil fuel is being consumed, albeit gently.

Indeed, if you have slightly farther to go, it's best to enter your destination into the sat-nav, because the car 'knows' the route, including topography, and will constantly adjust the hybrid system so it's working at its most efficient for the conditions.

The car can even give your foot a gentle nudge through the accelerator pedal to let you know when it would be best to ease off the throttle in the interest of efficiency.

It's clever, and it certainly seems to work. What Car? had the chance to put the system through its paces on the road and the numbers at the end suggest that a real-world average mpg figure of at least high-50s mpg should be possible. That's deeply impressive for a vast, heavy, petrol-powered, long-wheelbase luxury car.

Everything else is as you'd expect from an S-Class. The steering is light but accurate and the ride at speed is very comfortable indeed. The air suspension does get caught out occasionally by sharp bumps and ridges in town though. It's a shame that Merc's Magic Body Control suspension, which keeps the car level over all bumps, is unavailable on this model.

What's the 2014 Mercedes S500 Plug-in Hybrid like inside?

Ease yourself into the front seat of your S-Class and no matter the fact that you've just shelled out £87,965 (plus whatever options you choose, and there are many) you'll feel like you've got a pretty good deal. It's put together with the sort of care and materials that make Blenheim Palace feel a little 'slung together'.

Should you prefer to occupy the rear seat while someone else does the tedious driving bit for you, you'll be pleased that the S500 Plug-in Hybrid comes in long-wheelbase form only, so there are acres of space to stretch out in. 

It all feels beautiful, too. The leather for the seats appears to have come from cows that have never had to do a hard day's work in their lives, and there's loads of standard equipment, including climate control, a front-seat memory package and online connectivity. The rear seats are also heated, and you can even warm or cool the car's interior via a smartphone app before you get into it.

Of course, Mercedes will always be happy to relieve you of thousands more for various options, such as a deeply powerful Burmester audio system or a vast glass roof so you can see more of the sky you're helping to keep clear.

If something has suffered slightly with the fitment of the hybrid system it's the boot, because the batteries take up a fair chunk of space. It's big enough, but only just.

Should I buy one?

The S500 Plug-in Hybrid costs a full £17k more than a long-wheelbase S350 Bluetec diesel in AMG Line trim, so it's always going to be more of a niche choice. The diesel has all the space of the hybrid and does 50.4mpg on paper.

Still, the S500 Plug-in Hybrid hits back with free entry to the Congestion Zone, much lower company car tax costs and, of course, that incredibly refined motive experience. If your commute regularly involves city traffic, it's unmatched.

Our money, as will most people's, would still go on the diesel, but we can see why the S500 Plug-in Hybrid could prove a desirable alternative.

What Car? says...

Rivals

BMW 7 Series Active Hybrid

Tesla Model S

Mercedes-Benz S500 Plug-in Hybrid

Engine size 3.0 V6 turbo petrol

Price from £87,965

Power 436bhp

Torque 479lb ft

0-62mph 5.2sec

Top speed 155mph

Fuel economy 100.9mpg

CO2 65g/km