The Mercedes-Benz New Actros is already beating the fleet average fuel return by a full two miles per gallon for Ken Mallinson & Sons.
The South Yorkshire haulier is running 10 New Actros 2545 tractor units, including two of Britain's first ultra low-emission Euro 6 models.
The trucks feature 2.5-metre wide, flat-floored BigSpace cabs and are powered by 450hp engines, which drive the latest Mercedes PowerShift 3 automated transmissions.
Mallinson's Business Development Manager Ian Egan revealed: "Within the first two weeks one of the Euro 5 units came back with an average of 10.65mpg, and the Euro 6s were recording 9.7-9.8mpg.
"We carry a lot of plastic products so we're not fully freighted all the time - but given our previous overall average of 8.4-8.6mpg these figures obviously made us sit up and take notice."
Based at Mallinson's purpose-built site at Barugh Green, near Barnsley, the New Actros are on nationwide general haulage work. They pull 4.5 metre-high curtainsiders and a selection of flatbed trailers, and are typically on the road for a week at a time.
Supplying dealer Northside Truck & Van, Sheffield, is inspecting and servicing the new vehicles under the standard, and free, two-year Mercedes-Benz Repair and Maintenance Contracts.
Ken Mallinson & Sons is a long-term operator of Mercedes-Benz trucks and most of its vehicles wear three-pointed stars. "They're tried and tested product," said Mr Egan. "We run Axor as well as Actros tractors and they're the most reliable trucks we own. We also have an excellent relationship with Northside and if we were to suffer any breakdowns, we know the cover from the rest of the dealer network is fantastic."
He continued: "The New Actros builds on the excellent reputation of the previous model and is a superbly engineered vehicle, with a cab that's certainly proving to be popular with our drivers."
New Actros was launched on the eve of the CV Show in April and Ken Mallinson & Sons ordered its trucks during the NEC event, making it the first customer in the UK to commit to the Euro 6 model.
Managing Director Stephen Mallinson said at the time: "We're a forward looking company and as Euro 6 is on its way this will be a good time for us to gain some experience of running them. It's been very positive thus far and as the vehicles bed in we expect the mpg to continue to improve."
Ian Egan added: "We are highly delighted with the new Mercedes-Benz product and the fuel performance is reaching a new level."