A supercharged Micra? Are they mad?

The Northern Echo: DIG this new Micra DIG this new Micra

CONSIDERING the calumny heaped on the new Micra by motoring critics recently you’d think Nissan would steer clear of anything that could make it the butt of yet more vilification.

On the face of it fitting a supercharger, like the one bolted to the Jaguar XKR, to a supermini like the Micra seems like the work of a lunatic.

To be blunt, the current Micra is to performance cars what Dawn French is to limbo dancing.

Despite this, the DIG-S has a technical specification that would have any self-respecting performance car fan drooling: as well as the supercharger, the engine is strengthened and lightened, the tappets and piston rings are carbon coated (a feature you’ll also find on a Ferrari 458) and the cam-lobes have what’s referred to as “nano surfacing treatment” to make them more efficient.

So what’s going on? Have the lunatics taken over the asylum and turned the Micra into a junior GT-R? Sadly, the answer to that question is an emphatic “no”.

For all the race-bred tech used in its creation, the Micra’s 1.2-litre three-cylinder powerplant still only makes 98bhp.

However, the little Nissan impresses in other ways that are rather more relevant to the likely Micra owner.

Its exhaust chucks out just 95g of carbon dioxide per kilometre (20g/km less than the standard engine) and thereby avoids road tax; the claimed fuel consumption of 68.9mpg is a startling figure for a car that runs on petrol and not diesel; and the lightweight internals mean it’s the smoothest three pot engine you’ve ever driven.

How has Nissan achieved all this? It’s all down to the supercharger.

The engine runs on what’s known as the Miller cycle, a process first patented by an American engineer called Ralph Miller in the Forties.

Old Ralph reckoned that conventional four-stroke engines used a lot of power compressing fuel and air ready to be ignited by a spark plug. He devised a method where the intake valve of an engine remained open as the piston began to compress the fuel. This made it easier for the piston to push upwards, albeit at the expense of some of the fuel being expelled from of the cylinder, and thus more efficient.

Miller cycle engines are more frugal than their conventional equivalents because they can run higher compression ratios but the downside to the process is a paucity of torque (pulling power). The solution is the good old supercharger which mechanically boosts the incoming charge and replaces the lost torque.

In the Micra the supercharger is mechanically de-coupled to save energy and fuel when it isn’t needed. You can hear it start to whine when you put your foot down and a second later there’s a modest, but firm, shove in the back as the extra torque comes into play.

Volkswagen was the first car company to play around with forced induction and small capacity engines as a way of extra better fuel consumption but its solution, a twin charger concept which uses both turbo and superchargers, is too complex and expensive to make. Persistent rumours suggest VW is preparing to pull the plug.

Nissan’s single supercharger is a simpler and more elegant solution. It transforms the Micra from a fairly hum-drum supermini into a small hatch that’s fun to drive. Granted, it’s still no junior GTi but there is enough poke to squirt it out of bends quick enough to surprise drivers of bigger, and supposedly better, machinery.

It’s a shame the shape is so epicene and the cabin so obviously built down to a price. For example, I was shocked to find it doesn’t have a 12-volt accessory socket. You can have one, or an MP3 player connection, but not both together as they occupy the same plastic hole in the dashboard - could it be that expensive to drill another hole?

Don’t bother with the most expensive Tekna version, either, as the giant glass roof, parking slot measurement and a CVT automatic are unnecessary bling. The parking slot gizmo is a kind of halfway house solution for people who can’t judge space. It doesn’t do the steering wheel twirling for you like the Ford and VW set-ups but it does measure a space and rate your likelihood of parking in it (although, as it doesn’t know how good a driver you are, it could still be tragically inaccurate). The display tells you if you have a good, difficult or impossible likelihood of making a successful park. There’s isn’t a display for “not a hope in hell”, however.

The DIG-S is the car the Micra should have been when it launched last year. Had this delightful three pot been available from the off I doubt the car critics would have been half as cutting.

It does, however, render the standard 1.2 utterly redundant to anyone apart from the terminally hard up.

SPEC: Engine: 1,198cc supercharged, three cylinder.

Max power: 98PS @ 5,600rpm.

Max torque: 105 lb/ft @ 4,400rpm.

Max speed: 112mph.

0-62mph: 11.3 seconds.

Co2: 95g/km.

Combined mpg: 65.7mpg.

YOU MAY ALSO LIKE: VW Polo TSI: Uses similar forced induction for good performance and decent economy. Expensive and complex. If anything goes wrong expect the bills will be terrifying.

Fiat 500 Twin Air turbo: Sensational looks and great build. Good performance too, but more expensive and not as cheap to run.

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