Diesel-sipper pick of Kia's Rio range

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The diesel ISG version is a stronger, more effortless all-round performer than its petrol cousin. Photos David Thomson

Does this car look in some way familiar? That's right, a white Kia Rio adorned with green wavy lines on its flanks and prominent ISG lettering at the base of the rear doors featured in Drivesouth late last year.

A peep under the bonnet will reveal what's new this time round: whereas last year's test subject was petrol-powered, this latest variant of the Rio is a turbocharged diesel.

Both variants are, as it happens, 1.4-litre machines, in which six-speed manual transmissions deliver power to the front wheels, and from there to the road via low rolling-resistance tyres.

As the decals suggest, both feature Kia's Idle-Stop-Go (ISG) system. This automatically cuts the engine as the car comes to a stop, and automatically restarts it as the driver selects a gear in preparation to move off again.

Fuel saving is the aim of the game here, and those who are serious about it should be drawn to the diesel, albeit at the cost of a $2000 price premium over the petrol's $22,990 tag.

That extra investment should net a reduction of close to 20% in fuel use, the diesel's 4.3-litre per 100km standard economy cycle return comparing with a 5.3-litre per 100km figure for the petrol Rio ISG.

I could provide the results of some equations at this point, to demonstrate the point at which - with road user charges also allowed for - the diesel's economy and fuel price advantage overcomes its purchase price premium.

However, there is another reason for selecting the diesel ahead of the petrol Rio ISG: it is the stronger, more effortless all-round performer. This has everything to do with torque - the diesel delivers so much more of it: 220Nm as opposed to 137Nm, and it hits that peak from low in the rev-range - starting at just 1750rpm and running to 2750rpm.

As a result, once you get beyond initial throttle response, where petrol is sharper, the diesel reigns supreme: more torque equates to greater accelerative vim, and the spread of that torque provides a mechanical flexibility that keeps gear-changing duties to a minimum.

Like its petrol counterpart, the diesel puts ease of use and comfort ahead of razor-edged handling; fine ride and light controls count as two strengths in this respect.

On the downside, its tyres transmit considerable coarse-chip road noise and contribute to a tendency for early understeer during hard cornering.

 

Diesel-sipper pick of Kia's Rio range
At a Glance

KIA RIO 1.4 DIESEL ISG MANUAL

For: Neat styling, interior space, decent performance and superior economy

Against: Coarse-chip road noise, handling lacks sparkle

Verdict: The pick of the Rio range

SPECIFICATIONS

Price: $24,990

Engine: 1396cc four-cylinder CRDi turbo-diesel with integrated idle-stop-go (ISG), max power 66kW@4000rpm, max torque 220Nm@1750-2750rpm

Transmission: Six-speed manual

Brakes and stability systems: Disc/drum brakes, ABS, EBD, BAS

Wheels, tyres: Steel wheels and 185/65 R15 tyres

Fuel and economy: 4.3 litres per 100km (on European combined cycle), capacity 43 litres

Dimensions: Length 4045mm, width 1720mm, height 1455mm