When I was a kid, my dad drove a Citroen SM.
http://en.wikipedia.org/wiki/Citroën_SM
It was fairly "high tech" for an early 70s car... Fuel injection. Variable power assist steering. Hydraulic suspension.
NOT a fuel injected engine. No injection electronique cars wereofficially imported to the USA by
Citroën. This engine has three 42 DCNF (doppio corpo = double body (throat) + N (dunno) + F = Ferrari; the series was originally designed for Ferrari models) carburetors. One throat is piped to each cylinder with no interconnection manifold (other than tiny tubes for the emission control system) between the pipes.
The original air filter housing has been replaced with an aftermarket model. The original filter was an oil-wetted type, great for airflow but not so good for keeping dirt out of the engine. I had a custom paper filter element made for one of my SMs. I would move it to whichever one I was going to be driving.
The power assist is NOT "variable". The steering is full power with no mechanical connection between the steering shaft and the steering rack (except for emergency if the hydraulic pressure fails). It is the centering force on the steering shaft/wheel that varies with the speed of the pinion (secondary or lower) shaft in the transaxle. As the car goes faster, the centering force increases, making it harder to turn the wheel away from center. Full system hydraulic pressure is applied to the rod side of the steering rack piston at all times. The pressure to the piston head is regulated to move rack back and forth according to steering position.
While we call it "hydraulic," literally meaning having to do with water, the fluid is actually a specialized light oil called "LHM" (Liquide Hydraulique Minerale).
As you got up to highway speeds the car would "squat" lower to the road for better handling and aerodynamics.
The car does not "squat" as the height of the front and rear of the body is stabilized by the height controls, one for each end of the car. The normal position is the normal riding height/road clearance. There is a higher position for driving on rough roads and semi-roads and a low position used in wheel changing (and in amusing oneself, and amazing onlookers). There is a high position, also part of the wheel-changing procedure, and for negotiating the car over abrupt humps in driveways, etc. to prevent scraping the underbody and damaging the exhaust system. The car can be moved in low and high positions but only at low speeds as there is no suspension travel, only tire deflection and suspension arm flexing. Yes, you can "limp" on three wheels in high position with one rear wheel removed. It is all too easy to strike the rear brake shield on the road when doing this, so it can be advised only if you have suffered two flat tires.
If you had a flat tire you just flipped a lever and the car raised itself on the 3 good tires, leaving the flat in the air to be changed without needing a jack.
The system will NOT lift one wheel off the road. It will lift both wheels on one side if the wheel changing stand is supporting the frame by the peg on the middle of the sideframe. The car cannot be moved even if the engine is running and put in gear, as the front wheel that is off the road will just spin. (Dangerous - the spinning wheel turns at twice the speedometer reading: 40 mph on the meter is 80 mph on the wheel. It would positively kill anyone who got into it.)
The braking system was a bit extreme. It had a button rather than a pedal. It was almost an "all or nothing" affair.
Once accustomed to the chiefly pressure-sensitive and very short travel pedal (mostly "squash" of the rubber pedal cover), the brake action is marvelous! The brake pedal is lower than the accelerator pedal when the throttle is closed. As you do not have to lift your foot above the pedal, you can get your foot off the accelerator pedal and onto the brake "mushroom" very quickly. Unfortunately, if you drive both a
Citroën D or SM and conventional cars, this can be quite disconcerting.
Citroen has been a very creative car company, but I think their reliability has been fairly poor over the years.
Mostly due to poor maintenance and repairs outside of western continental Europe. Few technicians in North America were familiar with the car.
Citroën techs were faced with the unfamiliar Maserati engine. Maserati techs for the most part did not want to work on the Mas engine in a
Citroën, especially the way it was set so far back in the engine compartment. They also did not like the
Citroën equipment on Citroën-era Maserati Meraks and Boras, but they sorta had to put up with that. When a doctor or lawyer bought a Citroën SM from their local Oldsmobile dealer, he was soon ready to get rid of it. The local Citroën SM dealer in Nashville, Tenn. was a Mercedes-Benz dealer who had never sold or serviced any other Citroën models, not even the DS, which had the same basic chassis and machinery outside the engine. He sold 7 of them and kept one. He relied on one Benz tech who showed a fair amount of interest in the car. All parts had to be ordered from the Citroën parts depot in New Jersey as none were kept in stock.
Owners, especially original, soon tired of the difficulties of maintenance when no really dedicated
Citroën-Maserati tech was near. Many, after the novelty wore off, also became disappointed in the lack of tire-burning power of the "tiny" 170/181 cubic inch (2.7/3 litre) engine, due to the combination of the engine's power and that 2/3 of the car's 3,200# weight was on the front/drive wheels. They also expected more speed in a car that cost twice as much as a Cadillac Eldorado.
(Perhaps too much complexity and experimentation going on there). ppppp