This is about as big and luxurious as sub-100g/km cars get. Along with sister brand Citroen‘s DS5, the Peugeot 508 Hybrid4 saloon falls under the current lowest BIK point, and as it’s a diesel hybrid, doesn’t suffer the additional 3% that regular diesels are afflicted by, so offers a 10% banding.

It uses PSA Peugeot-Citroen’s EGC automatic gearbox that cuts emissions, but suffers from a lurchy and erratic shift and is way below the standards of regular automatics. The interaction between the diesel engine and electric motor is also flawed, and leads to the diesel revving away almost at odds to what the driver is doing with the throttle. But the car will run purely on the electric motor for short periods at lower speed, offering serene silent progress and no fuel use at all, while the electric motor powers the rear wheels and the diesel the front, offering four-wheel drive security for the winter months.

Unlike the 508 RXH, which is raised and clad in plastic off-road protection, the saloon Hybrid4 is almost imperceptible from a petrol or diesel model, although the taxman will feel the difference. Based on the Allure trim, it will leave 40% taxpayers with a monthly BIK bill of £105, compared with an auto Allure 163hp TDI’s £194. And that’s on a P11D of £31,395 for the Hybrid4 versus the diesel’s £25,310.

But overall, that price difference does for the hybrid on whole-life costs – as does a poor RV from KwikCarcost of just 23.1%, which is very high for a £30k-plus car – and 69.4ppm isn’t as impressive as the car’s 95g/km of CO2.

The car’s hybrid technology impresses on paper with its efficiency, the car is well kitted-out, and if it is to spend significant time in low-speed urban traffic, hybrids such as this can have a significant impact on fuel use and running costs. If it’s just for running up and down motorways, efficient diesels still make plenty more sense, but diesel hybrids have an argument if the usage patterns fit with the technology’s strong points.

Peugeot 508 Hybrid4
P11D price £31,395
Model price range £18,265-£33,640
Fuel consumption 78.5mpg
CO2 (tax) 95g/km (10%)
BIK 20/40% per month £52/£105
Service interval 20,000 miles
Insurance (1-50) group 33
Warranty 3yrs/60,000mls
Boot space 473 litres
Engine size/power 1997cc/200hp
Top speed/0-62mph 130mph/9.0secs
On sale June 2012
Score 8/10
Verdict The figures impress,
but the powertrain is
to get them