The 178bhp generated by the 508’s most powerful 2.0-litre diesel motor (the same as you’ll find under the bonnet of the Mondeo and Citroën’s C5, incidentally) puts it bang on the money in this sector. Every serious rival of the Peugeot has an engine of similar size and/or power output, while the 150g/km of carbon dioxide it emits is competitive too.
Subjectively, this engine is just as impressive as it is in objective terms. It starts quietly and settles to a muted idle. Power delivery is impressive, too; from low revs it pulls without fuss and with significant oomph the more you ask of it. At our test track this 508 pulled itself from a standstill to 60mph in 9.6sec. Just as significantly, it reached 70mph from 30mph in just 9.7sec.
The 508 RXH delivers the lowest emissions of the 508 range, at 107g/km, but it is also the most expensive, at £33,695. With 197bhp, it is nearly as fast to 60mph as the 508 GT at 8.8 seconds, but our issues with the automated gearbox remain; it is too jerky and hesitant to allow smooth progress.
Which hints at an important reality that will quickly become unmissable to a lot of 508 drivers: the car’s manual tranmissions are much better than the autos. Take the torque converter auto teamed with the 161bhp HDi: around town and when manoeuvring the gearbox is acceptable enough. The delivery, shift quality, amount of creep and step-off from rest are all smooth.
But at higher speeds, even if you’re just tooling around and not pressing on, the shifts are sluggish and the 508 frequently allows itself to be caught in the wrong gear. You can counter some of this by changing gear yourself, in which case the 508’s gearbox is very obedient to manual override demands, but this does rather defeat the object of having an automatic in the first place. Rivals do it better.
No complaints, however, about the 508’s brakes, which have both good stopping power and resolute staying power. Good pedal feel makes for easy, smooth stopping.