What is it?
This engine could be the new Laguna’s saving grace. It’s the 173bhp version of Renault’s 2.0-litre turbodiesel (also available in 128bhp and 148bhp form) and is the flagship of the Laguna range.
What’s it like?
As in the 148bhp version, twin balancer shafts mean a smooth, free-revving power delivery, and refinement in the cabin is impressive. Only BMW and Peugeot-Citroën make comparably smooth diesels.
The high torque peak of 2000rpm makes for a pretty narrow powerband, and the engine can feel lethargic below this point. But as long as you don’t get caught in the wrong gear, 280lb ft of torque is enough to shift the Laguna along at a decent lick. We’re not talking six-cylinder BMW and Audi diesel levels of performance, but it feels a step above a Mondeo TDCi 140.
Real torque junkies will be disappointed, however – Renault engineers say the transmission’s CV joints won’t take any more than 280lb ft.
The downfall of powerful four-cylinder turbodiesels is often surprisingly poor fuel economy. Not here. Renault claims a combined mpg figure of 42.8mpg. We only managed 37.6mpg over a mixture of winding A-roads, motorways and urban sprawl, but our long-term Mondeo TDCi has only been returning 39mpg, and the Laguna dCi 150 that we road tested returned 40mpg.