Suzuki Swift receives green new 1.2-litre engineSuzuki is introducing a new 1.2-litre petrol engine for the Swift supermini that is so green, it makes the car VED road tax exempt.

The new 90hp 1.2-litre Dualjet motor sits alongside the existing 94hp 1.2-litre motor and will cost £500 more when it’s introduced in early 2015. Initially, it will only be offered on posh SX4 models (pictured above) but will gradually be rolled out across the rest of the range.

To compensate for the drop in power, the engine gets a slight boost in torque, with peak pulling power produced lower down in the rev range too.

Suzuki says the new Dualjet engine returns 65.7mpg on the combined cycle, which is 9.2mpg better than the regular 1.2-litre motor – a hefty 16 per cent improvement. A big part of this improvement is down to standard engine auto stop start and revised gear ratios, but the new twin injector Dualjet technology also plays its part.

The key is placing the twin injectors close to the engine inlet valves, which allows the fuel to be better atomised. This means it can enter the cylinders and burn more efficiently. Suzuki’s also fitted new piston crowns and a revised exhaust gas recirculation system – which actually raise the compression ratio of the engine from 11.0:1 to 12.0:1.

The new Dualjet petrol engine makes the Swift one of the few regular petrol cars to emit less than 100g/km CO2. To date, diesel cars have largely enjoyed free road tax benefits but this may be under threat as legislators look to clamp down on non Euro 6 diesels to tackle inner city pollution. Green petrol engines such as Suzuki’s new motor may thus become increasingly significant in coming years…