Peugeot 604 SL
Reviewed by Unique Cars and Parts
Our Rating: 2
In 1975, some five years after the agreement was signed that led to the birth of the Franco-Swedish engine company, comprising Peugeot, Renault
and Volvo, the V6 engine appeared. The design of the engine was originally set in motion more than seven years previously, and the first customer for the 2.6-litre V6 was, naturally enough, Peugeot, who chose it for the 604.
-designed 604 was unveiled at the Geneva Motor Show in March 1975, with sales beginning in September of that year. It was based on the chassis of the Peugeot 504, using its doors, and represented Peugeot's first entry into the large luxury sedan market for 40 years (the last being the short-lived Peugeot 601 of 1934).
By European standards the 604 was quite a large car, with an overall length of 15.48 ft (4.71 m). Its design features remained in the classic style of the then current Peugeots, the line only broken by the massive bumpers. The 604 had an air of quiet assuurance, uniting a certain distinction usually found in cars of this class, with the tradiitional Peugeot dignity.
Technically, the 604 was a development of the 504
, and the rear-wheel drive saloon inherited the same well thought-out suspension
. However, an improvement had been made in the damping out of vibration and excessive movement of the rear axle.
The interior of the 604 offered plenty of space, with 4.85 ft width fore (1.48 m) and aft providing a useful space from toeboard to the back of the rear seat of 6.26 ft (1.91 m). The seats, of nylon velour, were luxurious and well-designed, but the mediocre dashboard was unworthy of a car of its class. Although reasonably complete, there were two important gaps: no maximum limit markings on the rev-counter, and no warning light on the petrol gauge.
The four courtesy lights were a sound feature of the general equipment, as was the efficient heater, which could deliver warm air to the back seats. Other features included inertia-reel seatbelts, fitted with energy absorbers (a Peugeot-Renault
specialty), and a laminated windscreen. On the other hand, it seemed a pity that on a prestige car the steering
wheel was so large and not adjustable for height, nor was the driver's seat, although the runners were curved.
It would also have been in keeping with the 604's class if an intermittent switch had been fitted to the wipers, and a central locking device made standard.
The Oversquare Engine, And Crude Solution To Vibration
The engine took a long time to develop, due mainly to the aluminium construction. The V6 engine itself was "oversquare
", a 90 degree
design chosen with the view of later developing a V8 from it - a project which was subsequently abandoned. The oversquare engine design was bound to introduce unwanted vibration, so Peugeot (and Renault
) suppressed the vibrations via the crude solution of introducing a two degree difference in timing between each bank of cylinders. The engine breathed through carburetters, and not only was its power-output disappointing, but also, which was more serious, torque was best described as modest. In comparison with other six-cylinder engines, the 604 developed 51 hp/litre (38 kW/litre) and 152.53lb ft maximum torque (21.1 mkg) at 3500rpm, which put it last in the category - and by todays standards it would at best be described as lethargic.
Fortunately, the engine torque curve was good, and when accelerating from 1500 rpm, there was an agreeable liveliness. However, pick-up was much too slow, and the petrol consumption too high, being around 14 mpg (20 lit/100 km).
In all other departments, the Peugeot merits nothing but praise. The manual gearbox was good, and so was the automatic transmission
, the steering
was precise, and sufficiently sensitive, thanks to variable-rate power assistance. Roadholding was good, the normal understeer becoming neutral at the limit. Lighting was powerful, road and engine noise very low, braking well-balanced, and above all the ride and passenger comfort were exemplary.
The Peugeot 604 is not particularly collectable, however for the time it was refined and well polished in most areas. Disappointing then that the main feature of the car, the V6 engine, was such a let down. Build quality problems added to the cars woes. Sales, which were never particularly strong, dipped in 1980 following the launch of the 505, and the last 604 rolled off the production line in 1985. Peugeot's next major executive car, the 605, was launched in 1989.
An In-Depth Look
The injection of a 604 into the 1975
Geneva Motor Show wasn't just a gesture to show that Peugeot was not too far behind Volvo and Renault in producing a large car with the jointly-developed V6 engine - Peugeot was more worried by buyers holding off from committing themselves to the 504 until they'd seen the new model. The 504 Pininfarina had suddenly acquired the V6 power unit – and some thought maybe the 504 sedan would too. But they were wrong. The 604 was a very different car, further up-market, aimed at government officials (perhaps even the French President), the diplomatic corps and those well-heeled citizens who put up with punitive taxation to buy imported Mercedes Benz cars. On the political and diplomatic scene, Peugeot backed it both ways, because there was also a long wheelbase Citroen CX Prestige in limited production, which also saw the fate of nations is being debated.
The 604 used the front doors of the 504, and Pininfarina collaborated on the body design (as it did on the 504) but it was a different car, of classic angular profile - very different too from the hatchback Renault 30 TS which used the same engine. It was a hushed and luxurious five-seater with deep soft seats that gave the right lumbar and lateral support. Front backrests were adjustable and all seats had head restraints. French designer Paul Bracq left BMW for Peugeot after the body design was finalised but arrived in time to do the interior and some echoes of BMW were suggested by the simple, clear instruments, the sensible minor controls and the neat retraction of safety harness into the front door pillars.
Projecting from the facia under the wheel were two levers: one for indicators, which was also pulled for the horns and the other for lights and wipers – the latter having parallel arms pivoted near the centre of the car, covering a big area, and designed to stop them from lifting off at speed. In the centre were switches for heated rear window, hazard warning and the electric sunroof. On the console were heater-ventilation slides and switches for the electric windows, including the windows in the rear doors. There were reading lights below the fascia and in the rear quarters.
The protective rubber-faced strips along the sides of the car were minimalist – long before the time when they were to be done away with completely. The smaller design of these protective strips resulted in a scrappy appearance by the chamfered ends wherever they met a wheel arch or a door edge. This was amplified by the fact that the wheel arches themselves were not strongly defined. As detailed above, the engine was a 90 degree V6 with a light alloy block and heads and a single chain-driven overhead camshaft each side. It inhaled through two Solex carburettors, one single barrel, one compound, and produced 100 kW at 5750 rpm and maximum torque of 206 Nm at 3500 rpm. The fan had a viscous coupling. Cars with automatic transmission had an additional electric fan, thermostatically switched, and copper fins on the radiator instead of steel.
was strut-type with the spring slightly offset, but was otherwise conservative. There was no offset of the bottom pivot and it didn’t use the anti-roll bar as one arm of the bottom wishbone was on some cheaper Peugeot models. Wishbones were manufactured of full forged steel and the anti-roll bar is separate to avoid complications if a bar should break on a car of this performance. Rear suspension, by semi-trailing fully boxed wishbones and coil springs, was more elaborate than that on the 504. Enormous care had been taken to damp out noise and vibration and prevent rear-end steering.
The anti-roll bar was insulated from the wishbones by links with rubber at both ends. The sub frame rested on rubber cushions with side pads to damp lateral shake. It also had two circular vibration dampers and as an additional precaution to prevent tilt or twist, which could put the rear wheels off course, there were two arms extending to further mountings behind the differential. Finally, the propeller shaft was enclosed in a torque tube, so torque reaction on the differential would not tweak the sub frame and derange wheel camber at critical moments.
was power-assisted rack and pinion with a hydraulic damper. Brakes
were ATE-Teves ventilated discs (with twin-piston callipers) at the front and Girling discs with single-piston raliner; at the rear. They were fitted with servo assistance, separate circuits front and rear, a load-sensitive valve to regulate rear brake pressure and electrodes in the pads to flash a warning light when the pads needed renewing - all of which demonstrated the safety thinking that had gone into the design. The structure was strongly reinforced, with crumple zones at front and rear. The big bumpers were rubber faced and had resilient end buffers. Heating and ventilation included face level fresh air and side window demisting at each end of the fascia and separate warm or cool air grilles in the centre. Air conditioning was among the options.
Behind The Wheel
Visibility was excellent, with a rear window as wide as the windscreen and all four corners of the car easily seen from the driving seat. Steering was light but gave good road feel and the care taken to control movement of the rear wheels accurately really payed off on fast bends taken at 150km/h, where the 604 would hold its course perfectly. At 3.5 turns from lock to lock, with a turning circle of 11.5m, the car was easily placed neatly on narrow winding roads. Tyres were either Michelin XAS or Dunlop SP Sport 175 HR 14 with tubes. Road testers would thrash the brakes looking for a weak spot, but most failed to find a point of fade or even get them to smell hot. Only true abuse could elicit these characteristics.
Rear seat comfort was outstanding, there was generous head and leg room and no road rumble to mar the enjoyment. There was a lot of luggage space too - about .405 cubic metres of usable space in the boot, though the bags had to be lifted over a fairly high sill in the interests of body stiffness. The change on the four-speed manual gearbox was a bit heavy - but owners reported that it freed up with use.
There were no guide marks on the tachometer
, which read up to 8000 rpm, but taking 6000 as a limit gave speeds in gears of 54, 91 and 133km/h. The claimed 182km/h was well within reach. The 0 to 100 km/h dash took around 11.5 seconds for the average driver – although experts managed to get this down to 10.8 seconds, with standing 400m in 17.2 seconds. DIN fuel consumption was quoted as 12.1 litres per 100km. A 90 degree V6 was never going to beat a good six in-line for smoothness, but apart from a trace of shake when idling it was very well insulated and the 604 cruised smoothly and quietly at 160km/h with only a whisper from the wind. There was surprisingly little buffeting at speed with the sun roof open, and hardly any in the rear.
GM's Strasbourg-built automatic transmission
was an optional at extra cost and it worked well. The engine
made itself heard in first gear and the selector positions on the central quadrant were not firmly enough defined to encourage a lot of manual changing for twisting roads, but the automatic changes were very smooth. Standards were high and this car represents a sound classic automobile that will not break the bank. Unfortunately few remain today.