The promise of tiny fuel bills and lower tax will be enough to tempt many buyers. Those who take the plunge will find a smooth, refined city car that’s almost as much fun to drive as the petrol model and visually identical. The extra torque means the Swift diesel is great on motorways, but the limited space and added expense will be hard to justify for most. We still think the petrol version is the pick of the bunch.

One of our favourite superminis now comes with diesel power – and Auto Express was first to get behind the wheel of Suzuki’s new Swift DDiS. Can it provide lower fuel costs without spoiling the fun-filled driving experience?

Soaring fuel prices mean more and more manufacturers are offering an oil-burning option in their small cars. However, as Suzuki doesn’t build any of its own diesel engines, the 74bhp 1.3-litre unit is borrowed from the Vauxhall Corsa instead. Economy of 67.3mpg is impressive, as are the 109g/km CO2 emissions.

Video: watch CarBuyer's video review of the Suzuki Swift

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Although the diesel isn’t as quick off the line as its petrol counterpart, it produces an extra 70Nm of torque, at 190Nm. As a result, the car is faster in everyday driving conditions and on the motorway. It’s also surprisingly quiet and smooth – clatter is well suppressed from the cabin, thanks to added sound insulation.

The superb handling and comfortable ride are unaltered, while the extra 105kg on board hasn’t affected the Swift’s agility. It’s settled over uneven surfaces, and the chassis still provides lots of entertainment. Through bends, there’s plenty of grip, with well weighted steering.

It’s not all good news, though – as with most diesels, the DDiS carries a premium. At £12,890, it’s one of the most expensive models in the range – the top-spec SZ4 petrol is £385 cheaper.

To ease the financial blow, Suzuki is offering the diesel only in well equipped SZ3 trim, although it does without cruise control and a starter button. It also lacks the wonderful, free-revving nature of the petrol car, which is perfectly suited to the go-kart-style handling.

Unlike the Corsa ecoFLEX, which uses the same engine, the Swift isn’t exempt from road tax – as it emits more than 100g/km. Only high-mileage drivers will be able to justify the extra expense.

It’s not the most practical supermini, either – there’s room for five on board, but this comes at the expense of luggage space. Although the back seats fold to create more storage, the narrow 211-litre load area is only really suited to small shopping trips.

Ultimately, though, these niggles don’t detract from the fact the supermini is a decent buy, whichever fuel it’s powered by. And as the DDiS has the lowest running costs of any Swift, it’s sure to attract plenty of buyers.