Both will offer new fuel-saving technologies, including a unique diesel-electric hybrid powertrain (HYbrid 4), which is also destined to appear in the 3008 crossover and possibly the RC-Z coupe.
HYbrid 4 has a diesel engine to drive the front wheels and an electric motor powering the rears, giving the car all-wheel-drive capability. Peugeot says CO2 emissions will be officially rated at 99g/km, making the car exempt from road tax.
What we don't yet know is what rate of company car tax it will attract: petrol-electric hybrids are taxed at 10% of list price, but diesels normally get a 3% loading over comparable petrol engines, so the hybrid 508 could be rated at 13%. Even the Government's revenue and customs department couldn't tell us how the HYbrid 4 508 will be rated.
Peugeot's HDI diesels and the turbocharged petrol engines developed with BMW will appear in the rest of the range, and there will be a new engine stop-start system, called e-HDI, which is said to be quicker in operation than the current one, improving driveability in traffic. Aerodynamics and weight-saving also play a big part in the 508's overall efficiency, Peugeot claims.
The 508 is based on Peugeot-Citroen's large-car platform, like the 407 and Citroen's C5, but is quite a bit longer than the outgoing car – 100mm in the case of the saloon and 50mm with the SW. Peugeot says the suspension has been set up with ride comfort and roadholding the priorities, but is not yet revealing whether there will be a hydropneumatic option like that in the C5.
Passenger and luggage space are said to be 'exceptional', while the drive to raise interior quality – evident in recent introductions like the 3008 and 5008 – seems to have been carried through to the 508.
Peugeot is promising plenty of standard equipment, and is likely to carry its familiar Active, Sport and Exclusive trim levels through to the newcomer, although no decisions on specification and pricing have yet been made.
Cars for European markets will be built in France, but the 508 will also be made in China for what has now become the world's largest car market.