Subtle badging aside, the HYbrid4 is hard to pick from other 508 saloons

Subtle badging aside, the HYbrid4 is hard to pick from other 508 saloons

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Is there another sedan sold anywhere with diesel-electric power and all-wheel drive? After a week with the 508 HYbrid4, Glenn Brooks believes he has found that rare car - one with no direct rivals.

The hybrid version is surely the sleeper version of the 508 saloon range. Even for incurable car spotters such as me or Mr Deputy Editor Roberts, it can be hard to tell if it’s a diesel-electric when you’re sitting behind a 508 in traffic. I’ve had a go in its brothers, the 508 RXH as well as the HYbrid4 versions of the 3008 and Citroën DS5 and somehow, the 508 saloon feels different. Where the DS5, especially, seems to be aimed at the enthusiast driver, the Peugeot feels more limo-like.

One of the aims of Peugeot UK bringing the car in to this market is to get fleets thinking about the advantages of diesel-hybrid vehicles. The story is a good one: CO2 emissions of 95g/km (107g/km for the 508 RXH) and for ‘user choosers’, a low Benefit-in-Kind taxation rate of 10% (12% for the RXH). For businesses, both vehicles attract 100% Capital Write-down Allowance, i.e. there is no further value to be carried over for taxation into the following year.

The HYbrid4 version of the 508 saloon has been available in Britain since last year. Powering it is the combination of a 2.0-litre four-cylinder turbo diesel engine and one electric motor. The front wheels are driven by a 163bhp (120kW) 2.0-litre HDi FAP turbocharged diesel, with rear wheel drive provided by an electric motor. The latter also allows an all-electric drive mode (no tailpipe emissions). Torque is claimed to be 500Nm and total power is said to be 200bhp. The transmission is an automated six-speed manual gearbox and stop-start also features.

PSA has packaged the hybrid system’s components carefully but you do still lose some boot capacity compared to the combustion engine only versions of the saloon. You also can’t have a spare tyre in the HYbrid4; it’s the only 508 saloon which comes with a standard puncture repair kit. The nickel metal hydride batteries are mounted beneath the boot floor, along with the electric motor.

You can drive in any of four different modes, one of which allows electric-only power, though the diesel engine will kick in under hard acceleration. Another activates both power units if constant four-wheel drive is wanted. You might be wondering why PSA hasn’t (yet?) launched a PHEV version of its HYbrid4 system but it’s worth recalling that when the 3008 diesel-electric went on sale in 2011 its technology was radical stuff. Perhaps a plug-in derivative of one of the existing HYbrid4 Peugeots and Citroën is on the way for 2014?

The manufacturing side of the story will be of interest to many readers as the hybrid versions go down the same line at Rennes-la-Jannais as other 508 saloons and estates. This plant in western France also builds the Citroën C5 saloon and estate as well as all versions of the DS5 sold in Europe. PSA and Changan's newly opened CAPSA joint venture factory in Shenzhen builds the DS5 for China but an older factory, Wuhan No.2 in Hubei province, makes the 508 saloon for the local market. There is even some 508 assembly in, of all places, Kazakhstan. The car has been put together there by PSA’s partner Agromash since the N.H. summer. It is assembled alongside the 308, 5008 and Partner at a plant in the city of Kostanay.

The 508 sedan is sold in North America, you might be surprised to know, though not the HYbrid4. Mexico is the car’s sole market in that region, sales having commenced in 2012 for the 2013 model year. With Europe, China, the Americas, Africa and the Pacific Rim covered, that leaves just India. Until April 2012, PSA would only say that a facility at Sanand in the state of Gujarat would build a Peugeot 'sedan'. This was an official response to multiple reports during 2011 and into 2012 of an imminent announcement on a new plant for the country. The first cars had been due to roll off the line in 2014 but in April last year, PSA suddenly said it might instead build cars in India at a GM plant. Since then....silence.

However, in October 2012, GM and PSA stated that a 'joint programme for mid-sized cars' would be one of four co-developed architectures to be launched 'by the end of 2016'. This platform was to be for Opel, Vauxhall, Peugeot and Citroën models. The likely PSA cars would have been the replacements for the Peugeot 508, Citroën C5 and DS5, while for GM it would have been the follow-up to the Opel and Vauxhall Insignia.

In December 2012, GM and PSA appeared to change their minds - there was no mention of a shared large car architecture when the firms issued a press release summarising future joint projects. What this now means is almost certainly that GM will develop its own Insiginia replacement and PSA will base its next large-ish models on EMP2, a newly introduced architecture. The Citroën C4 Picasso and Grand C4 Picasso, as well as the new Peugeot 308 are the first three models but many others will follow.

While PSA’s PF3 platform cars - 508, C5 and DS5 - are made at Rennes, the modular hybrid rear drive axle is assembled and supplied from another of PSA’s French plants, Mulhouse. GKN Driveline delivers electric drive system components to this facility for assembly in hybrid modules, and batteries are supplied by Sanyo.

The W23 series 508 is getting close to the mid-life part of its lifecycle, having been launched in France in 2010. Expect a facelift next year ahead of a further three to four years of production at Rennes.

To keep the current car fresh and lift sales ahead of that refresh, a few months back Peugeot UK added equipment to most model grades, and it revised prices. The HYbrid4 remains the top-spec car of the 508 saloon range with its trim more or less matching that of the 115bhp 1.6-litre diesel, 156bhp 1.6-litre petrol and 140bhp and 163bhp 2.0-litre diesel Allure versions. As for other engines, there is a base Access model grade car powered by a 120bhp 1.6 petrol, while the GT is the only 508 to be powered by PSA’s 200bhp 2.2-litre diesel in combination with fully automatic transmission.

What’s the price of owning the world’s only diesel-electric 4WD saloon? Here in the UK, it’s GBP32,100. For that you get keyless entry with Stop/Start button, cruise control with speed limiter, automatic parking brake with Hill Assist, automatic dual-zone air conditioning, electrically folding mirrors, Peugeot Connect Navigation (RT6) with Bluetooth, Peugeot Connect SOS and Assistance, automatic headlamps and wipers, 18" alloy wheels and half leather seats all as standard.

The driving experience is a little unusual in the HYbrid4. It moves off silently like a Prius and you also have a similarly unconventional gear selector in the form of a tiny lever which has markings for R, N, A and M but nothing whatsoever for those of us who like to see Park with what feels like an automatic transmission (you soon get used to this automated manual and there's no clutch pedal or gears to change). There’s always a slight pause when you floor the accelerator, which can be a little disconcerting the first time it happens but more welcome things with this car are the small steering wheel and that intuitive rotary controller for the AUTO, SPORT, ZEV or 4WD driving modes.

Don’t think I’ve ever seen so many buttons in a car’s interior. I lost count but they are just everywhere. There are four between the speedo and the power gauge (there’s no tacho), hazard lights and door locks are on the dashboard between some pop out cupholders, there are a further 14 on the console between the seats, plus another rotary control in addition to the drive system one, and a small pull-out remote control for the DAB radio. I prodded and peered but couldn’t find how to adjust the pitch of the head-up transparent polycarbonate panel which rises out of the top of the dashboard. Being a male, obviously I wouldn’t consult the handbook but then I saw what looked like a cover for a fusebox so tugged on that. Down flopped a box of more buttons (!) just above my right knee. Need to turn off the stop-start or ESP? You’ll find the controls here as well as the head-up display adjusters.

The did something unusual on my watch: it defied gravity. I live in Bath, and you enter this small city encircled by hills along any number of long, downward sloping roads, steep in parts. The one I use often for the 20 minute run from the motorway has a 30mph limit for its last half mile - the Park & Ride buses always have their brake lights aglow ahead of you for this ever steeper stretch of road.

The drag on the regenerative brakes is so strong that in the 508, coming over the brow of the hill before the descent into the city, I lifted off from 60mph and got ready to brake but the car soon began to lose a lot of speed. There was no-one behind me so I just stayed off the brakes, kept checking the mirror and eventually the car slowed to an indicated 5mph even as the road stayed steep. I wished I could have got the Peugeot to finally stop itself on that hill but alas I saw some headlights in the distance behind me and had to accelerate to get down the last steep part of the journey to the centre of town. Extraordinary. The ‘% Power’ gauge was loving all this and by the time I got home 10 minutes later there was loads of juice to use in EV mode.

Finally, some performance and economy data. Max speed is quoted as 130mph, zero to 100km/h or 62mph takes a claimed 9.0 seconds. My last thought: I’m left feeling fascinated by a braking system that has been designed to recover so much kinetic energy that it, aided by the automatic reversal of the electric motor's drive, can slowly but surely stop 1,815kg plus 78kg of me without one touch of the left pedal. The Urban average is 80.7mpg or 78.5 for the Combined cycle. I’m normally sceptical of these official numbers with hybrids but the 508 has convinced me that driven the right way, you really can see spectacular economy in this car. I wonder how long the electric motor will last, and how often you have to change the brake pads?