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Mercedes F700 news - Frankfurt show: Mercedes F700

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One of the undoubted stars of the Frankfurt show
isn’t a car at all, but rather an engine: the DiesOtto in the Mercedes F700.

Not that the F700 is anything less than imposing (and more
about that in a tick). But if the DiesOtto’s performance and economy turns out
to be even close to what Merc is quoting, well, it could revolutionise the combustion

In brief, the DiesOtto is a 1.8-litre, four-cylinder petrol
engine. That might sound small in a car the size of the F700 - which is longer
than an S-Class - but Merc reckons that it’ll produce comparable performance to
the current 3.5-litre V6 in the S: 238bhp and a 0-60mph time of 7.5 seconds.

And all that with consumption of just 44.3mpg and CO2
emissions of 127g/km - astonishing figures for such a big car.

It’s all down to the DiesOtto’s ingenious ignition system,
which combines the best bits of a petrol and diesel engine. On start-up, the
engine runs in standard petrol mode, with spark plugs igniting petrol injected
directly into the cylinder.

But once the engine is warm and cruising, it switches to a
more efficient ‘diesel mode’, raising the compression ratio and deactivating
the spark plugs.

Clever stuff, and it’s all sitting in a clever car. The F700
is described as a ‘research car’ that could preview the next-generation S-Class
and, with its giant pointed grille and 21-inch wheels, it’s a big beast.

The right-hand rear door is a suicide effort, opening
backwards to reveal a rear-facing seat (a bit like a London taxi, but without
the inane conversation) and an enormous TV screen. Equally oversized is the
driver information panel, which stretches across the dash behind the
squared-off steering wheel.

There’s loads of clever technology on board, too, including
a road scanning device housed in the headlamps that feeds information back to
the F700’s hydraulic systems.

But the big news is the engine, which Merc reckons could
make it to production within five years. Just imagine how economical it’d be in
something the size of a C-Class…

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