High & mighty: Diesel Luxury SUVs

Diesel has for decades been regarded as an agricultural fuel. It is, after all, a byproduct of unleaded petrol, the bottom of the fuel chain. But big gains in technology, emissions and efficiency have propelled diesel beyond the mainstream and into the high-performance category. Experimental diesel sportscars have even won the past seven LeMans 24-hour races (six of them by Audi, one by Peugeot) and car makers are finding new ways to take advantage of their newfound power.

Diesel still isn’t for everyone, though. The bowsers and the forecourts at refuelling stations are often greasy, and the smell of diesel seems impossible to wipe from your hands. But if you can live with these compromises – or know of an immaculate service station – one of this quartet of cars might be for you.

Porsche Cayenne S Diesel 

We only need to glance at the vital statistics to see fierce rivalry is alive and well in Germany. Having once said it would never build a diesel, Porsche now has two. But being last in also means being best dressed. That’s why the Porsche V8 turbo diesel (borrowed from partner companies Volkswagen and Audi) has 1kW more power than the BMW, at 281kW.

But the Porsche comfortably wins the battle over torque (the measure of an engine’s ability to overcome resistance), with a mammoth 850Nm. All this is enough to shove the Porsche Cayenne to 100km/h in 5.7 seconds (curiously, a fraction slower than the BMW, according to the official manufacturer claims). This is also only marginally slower than the top-line twin-turbo V8 petrol Cayenne that costs A$294,000. Talk about bang for your buck.

Conveniently, the V8 diesel Porsche is cheaper than the V6 hybrid version. And with a 100-litre tank it has a theoretical range of 1,200 kilometres between refills. I normally prefer hybrid power to diesel, but in this instance there is no contest. The diesel V8 is the way to go – unless you can stretch all the way to the turbo V8 petrol.

Price: A$155,500

Engine: Twin-turbo 4.2-litre V8 diesel

Power: 281kW and 850Nm

Transmission: Eight-speed automatic

Economy: 8.3L/100km

0 to 100km/h: 5.7 seconds

Volkswagen Touareg V8 TDI R-Line 

VW once had the world’s fastest SUV. The original Touareg was available with a massive V10 diesel engine (2007 to 2010). But sales didn’t exactly take-off, probably because it was ahead of its time, so Volkswagen let the idea rest for a while.

Well now VW’s back with a big V8 turbo diesel with a tonne of grunt. Not coincidentally it is the same engine fitted to sister company Porsche’s Cayenne diesel V8. The engine was jointly developed but the VW comes with slightly less power. This seems to have had little impact on performance; it is just 0.1 second slower to the speed limit than the Porsche Cayenne diesel V8 and costs A$43,000 less. As with the Porsche, the top-line Volkswagen Touareg is due on sale by the middle of the year. An orderly queue has already formed for both it and the Porsche.

Price: A$112,990

Engine: Twin turbo 4.2-litre V8 diesel

Power: 250kW and 800Nm

Transmission: Eight-speed automatic

Economy: 9.2L/100km

0 to 100km/h: 5.8 seconds

BMW X5 M50d 

The name might be a mouthful but the BMW X5 M50d is officially the world’s fastest diesel SUV. It can reach the speed limit before you can untangle the pronunciation of its badge. BMW has snuck “50” in the middle of its tongue twister – even though the engine capacity is 3.0-litres – because it has 5.0-litre V8 levels of grunt thanks to a triple turbocharger system, a class first.

The first turbocharger is electric and designed to create a lot of power at low revs (eliminating much of the initial acceleration delay that is typical of diesels). By the time it’s done, there is enough air blasting through the engine for the two other turbos to take over and thrust you towards the horizon. It’s an epic feeling, made better by the fact that the BMW is one of the best handling SUVs on the planet.

Price: A$147,500

Engine: Tri-turbo 3.0-litre in-line six-cylinder diesel

Power: 280kW and 740Nm

Transmission: Eight-speed automatic

Economy: 7.5L/100km

0 to 100km/h: 5.4 seconds


Mercedes-Benz ML350D 

The top-line Mercedes-Benz diesel isn’t quite in the same league as the other three vehicles listed here – but it has ample performance at a price that makes it a relative bargain among its peers. Sneaking under A$100,000 the ML350D delivers 90 per cent of the performance of its rivals but at about 60 per cent of the price.

The Mercedes-Benz is also among the roomiest of its rivals, for occupants and for cargo. The one area it truly excels, however, is ride comfort. Compared to its classmates the ML350D is a magic carpet ride, gliding over bumps that would make the others shudder. And yet it’s still competent in corners. Call it the best of both worlds.

Price: A$99,400

Engine: Turbo 3.0-litre V6 diesel

Power: 190kW and 620Nm

Transmission: Seven-speed automatic

Economy: 7.3L/100km

0 to 100km/h: 7.4 seconds

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