What's the point of paying thousands of dollars extra for a diesel engine in a baby car when the petrol-engine sister car is pretty frugal in the first place?
Perhaps the buyer wants to enjoy the torque character of the diesel engine, take pride in the ultra-low fuel usage and CO2 exhaust emission and hope the resale value in a few years might also help make up the gap in the extra paid for the diesel car when new.
In medium-size and large cars, especially heavier SUVs, a diesel engine can make sense in the money saved in fuel bills. But what about a baby car - such as the latest WT Ford Fiesta?
PETROL VS DIESEL
The entry-level for diesel is the Fiesta LX. The LX petrol costs $18,990. The diesel is $21,490. That is $2500 or 13 per cent more. The official fuel consumption figure for the petrol engine Fiesta is 6.1 litres/100km and for diesel 4.4 litres/100km.
So, yes, the diesel buyer will get his money back. How long that will be depends on the price of each fuel and the distance driven. If petrol and diesel are each, say at least $1.40 a litre, the petrol Fiesta will use $85.40 worth in 1000km while the diesel will use $61.60 worth of fuel.
That's $23.80 cheaper in the diesel every 1000km, so to recover the extra $2500 paid when buying the car, it will take 105,000km. If diesel prices are cheaper than petrol (rarely), it could take less; but if diesel costs more a litre than petrol (likely) it will take longer.
Taking the above example of 105,000km to get your money back, a baby car might average 12,000km a year so that's nearly nine years. To be fair, a diesel buyer could well be a higher-than-average distance driver so that amount of years will reduce.
In almost every respect the Fiesta LX diesel is the same as the LX petrol. The difference in their 1.6-litre engines is 89kW power and 151Nm torque for the petrol while the diesel gives 66kW power and 200Nm torque. Diesel Fiesta has a taller final drive ratio (our diesel test car cruised at 2500rpm at 110km/h). Diesel Fiesta comes with only a manual gearbox. Petrol Fiesta can have that five-speed manual or an automatic.
Glass's Guide research editor Richard Plumb says this will affect resale value. "The lack of automatic is a significant sales obstacle as consumers seeking economy are not always willing to sacrifice the convenience the automatic offers, especially in city driving which is where diesel offers the greatest benefit," he says.
He says a large SUV with diesel will have a better resale than with petrol; but on a small vehicle the fuel savings are less and the diesel option is a greater percentage of the new price. Glass's Guide expects petrol and diesel Fiestas to have similar resale percentage - 58 per cent after three years and 40 per cent after five years for the petrol, while the diesel would be 60 per cent after three years and 41 per cent after five years.
Servicing costs of the Fiesta petrol and diesel can be expected to be about the same, each at 15,000km/12 month intervals, each A-service listed at 1.3 hours and consumables such as filters about the same price. The diesel of course does not need spark plugs.
The diesel Fiesta weighs just 30kg more than the petrol. We still enjoyed its handling: for a sub-4m hatchback on 185-size tyres, Fiesta doesn't mind a twisty hills road. Diesel Fiesta LX has no stop-start and, like the petrol version, no spare wheel but is hard to fault otherwise.
Ford Fiesta LX hatch diesel (petrol)
Price: from $21,490 ($18,990)
Engine: Turbo 4-cyl sohc 1560cc (4-cyl, dohc 1596cc)
Power: 66kW @ 4000rpm (89kW @ 6300rpm)
Torque: 200Nm @ 1750rpm (151Nm @ 4300rpm)
Fuel use: 4.4 L/100km (6.1 L/100km)
CO2 emission: 117g/km (146g/km)
Size: 3950mm (L), 1722mm (W), 1454mm (H), 2489mm (WB) (same for petrol)
Weight: 1133kg (1138kg)
Final drive: 3.37:1 (4.07:1)