DAF Looks Good on Saving Fuel

Following the latest release in Europe, Diesel News Europe Correspondent, Brian Weatherley, reckons DAFs look good on saving fuel. He has seen them, and driven them. DAF says its latest CF and XF represent ‘pure excellence’. 

According to Ron Borsboom, DAF’s chief engineer, director of product development and board member: “One of the things where we feel we do a pretty good job is we are close to our customers, and we understand what the requirements and needs of our customers are.”

It also has to be said that DAF does a pretty good job too of building reliable trucks that earn its customers money. The one thing you won’t find the Dutch truck-maker doing is rushing to be first in the market with new technology or clever widgets. That’s just not its style. For DAF’s engineers at Eindhoven, the watchword is evolution, not revolution, and the latest CF and XF, said to deliver average fuel savings of up to seven per cent, are a perfect case in point.

DAF’s new heavies are all about steady, incremental changes rather than show-stopping leaps into the future. That aforementioned seven per cent average fuel gain comes from across-the-board improvements, not just on engines and gearboxes, but also aerodynamics, axles, emission control systems and powertrain control software. Drivers get a look in too, with new interiors and dash layouts. But if you’re a hard-pressed haulier desperate to improve your bottom line (is there any other kind?) the important news is better fuel economy.

Before getting stuck into the changes under the hood, it’s worth noting what’s different on the outside. Aerodynamic improvements to the front of both CF and XF include better grille closures and radiator flow guides that ensure the most efficient air flow around the vehicle and, equally important, through the engine compartment.

In short, it’s all about providing maximum cooling but with minimum drag – any air that doesn’t have to go through the engine compartment for cooling goes around the cab. That optimised air-stream is further aided by a tighter ‘cab-split closure’ (i.e. the gap between the bottom of the cab and chassis) and a more wind-efficient sun visor and front wheel-arch extensions.  Together, those aero tweaks deliver a 0.5 per cent fuel gain. ‘What…only 0.5 per cent?’ Just be patient and enter that figure into your calculator, because there’s more to come. 

The biggest fuel gains undoubtedly come from the latest 10.8-litre MX-11 and 12.9-litre MX-13 Euro-6 diesels. Both share improved combustion systems with reworked injector-nozzles and piston crowns, along with new piston rings and liners that reduce internal friction, and compression ratios have gone up from 17.5:1 to 18.5:1, further improving engine efficiency.

On MX-11 and MX-13 engines up to 480hp, there are new turbochargers and compressors too, while MX-13 gets a revised camshaft and new oil module. Together with those big-ticket changes, Borsboom confirms it’s “now about smaller areas.” That means a new generation of fully controllable variable pumps for air con, cooling, oil and steering that cut down on parasitic losses. Add-up all those engine improvements and you get a further three per cent saving on fuel.

That alone would be impressive were it not for the fact that the power and torque ratings on both MX-11 ‘Haulage’ and MX-13 engines have also been raised. What’s more, the MX-11 top rating is now 450hp, with 2,300Nm of torque (up from 435hp/2,100), while the most powerful MX-13 pushes out an increased 530hp and 2,600Nm (up from 510hp/2,500Nm).

Despite rumours from some quarters (i.e. the truck press) that MX-13 would get a more substantial power boost DAF steadfastly continues to resist calls to follow Mercedes, Scania and Volvo into 600hp territory. Given the relatively small sales volumes of prime movers in Europe with more than 550hp, it’s hard to fault their logic.