- The hydropneumatic conservation project

Choosing Your Hypcar

Owning and caring for a classic car requires genuine passion, but passion alone may not suffice. You’ll also need knowledge, plenty of patience, and a dash of financial commitment to truly enjoy the ride! So, before you plunge into the thrilling realm of hypcar ownership, take a moment to consider whether this is the adventure you really want to embark on. If you’re ready to hunt down that perfect hypcar, our dedicated sections and recommended specialised resources are here to guide you through their distinctive features and impressive technical prowess, helping you find a model that meets your desires and fits your budget.

The adventure of curating your very own hypcar begins the moment you acquire it, whether through inheritance, a deal from a private seller, winning it at an auction, trading for it, or even unearthing a hidden treasure in a barn. The car’s condition at the time of purchase will play a huge role in how you care for it down the road, including any restoration needs and associated costs. Inexpensive “opportunities” can often come with hefty restoration expenses. For example, a complete overhaul of a hydropneumatic suspension can easily set you back over €5 000. That’s why it’s essential to examine the hydraulic circuit closely during your pre-purchase inspection.

Make sure to check the self-levelling and height adjustment mechanisms and watch for hydraulic leaks. While some leaks, like those from cracked or torn suspension gaiters, are fairly common and generally not serious, leaks from the steering system or gearbox hydraulic command (like those found in the DS) can be more challenging to fix. You’ll definitely want to avoid dealing with multiple leaks at once! We highly recommend checking for any leaks before you commit to a purchase; even a budget-friendly reupholstered interior can create a false sense of a car in good condition.

During your pre-purchase inspection, make it a priority to check for corrosion and rust around and under the vehicle, focusing on areas like the sills, wheel arches, boot, and floor. To accurately assess the severity of any rust spots, it’s beneficial to familiarise yourself with the structural elements of each hypcar beforehand. Occasionally, what appears to be a major issue can be addressed with the right repairs. The photo series on the right highlights a boot floor predicament on a DS that was expertly resolved by replacing and properly treating the corroded panels. In any case, keep in mind that a body/chassis overhaul for a large hypcar can easily exceed €30 000.

Once you step inside the car, take a moment to check the upholstery and pay special attention to the condition and functionality of the instrumentation. Tracking down dashboard components for models like the GS/GSA, CX, and XM can be quite a challenge. Also, don’t overlook the window lifts—give them a test on all doors of the CX, BX, and XM models. The DS and GS feature virtually indestructible manual window mechanisms, while the electric windows in the SM can often feel agonisingly slow.

When it comes to hypcar engines, you can generally rely on their dependability—provided they have been well cared for by previous owners. An exception to this rule is the SM’s Maserati engine, which is notoriously fragile. The secret to determining an engine’s condition lies in its maintenance records and history, as well as any time it has spent idle. Remember, classic cars are not just for show; they deserve to be driven regularly, showcasing their status as collectible treasures while also ensuring their mechanical longevity. In the video below, you can see and hear a 50-year-old DS engine being tested during an overhaul.

The hydropneumatic suspension is what gives hypcars their signature ride quality. Therefore, it’s crucial to check that the hydropneumatic components—including fluids, gases, and rubber seals—are in prime condition. Two key checks you can easily perform are: (i) ensure the hydraulic components and circuit have no visible or audible leaks (the latter can often be detected by the frequent operation of the pressure pump), and (ii) confirm that the fluid and pneumatic components are in excellent condition. Look for clear green fluid using the gauge on the reservoir located in the engine compartment. You can evaluate the pneumatic components (spheres) by pressing down on each corner of the hypcar and observing their responsiveness and rebound. Most spheres also have their production date marked.

An assessment of a hypcar should always include a road test, even if it’s just a short one. After all, it is that exceptional ride feeling that makes the difference compared to the other mortal cars! During your drive, check the ease of start-up, how well the controls function, the car’s directional stability, and braking efficiency under sudden pressure. Additionally, assess the suspension’s suppleness. Ensure you engage all gears, including reverse. Be vigilant for any unexpected reactions, vibrations, or juddering, and listen closely for unusual sounds when navigating bumps and turns—watch out for rattling, clunking, humming, or grinding. These noises might indicate that bearings, bushings, or rods need lubrication, tightening, or replacement. Unusual sounds may or may not be felt through the steering wheel, which can help pinpoint their origin.

The following link on J. Cats’s website provides a comprehensive buyer’s guide to classic Citroëns: https://cats-citroen.com/citroen/buyersguide.html#gs

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Upkeep Tips

Classic cars require a bit more TLC than their modern counterparts, and hypcars even more so, as their mechanical and hydropneumatic components work in concert. In addition to basic maintenance, servicing and restoration are vital for keeping these beauties in peak condition. Unfortunately, restoration projects can come with a hefty price tag, as spare parts and specialised labour for classics can be quite expensive. To avoid unpleasant surprises and minimise the chances of a major service or complete overhaul, it’s essential to adhere to a regular maintenance routine—never skip it! While servicing and restoration may feel like a rollercoaster ride, maintenance is something you can easily plan and budget for.

That said, while shorter maintenance intervals can help offset the effects of low mileage for a hypcar, remember that some level of overhaul or renovation will eventually be necessary. However, diligent and thorough maintenance—coupled with the timely identification and resolution of issues before they snowball into major problems—can significantly reduce the chances of sudden breakdowns, prevent unexpected expensive repairs, and extend your vehicle’s lifespan. In short, being proactive is a valuable practice when curating your hypcar.

In the “Looking After” section dedicated to each hypcar, you’ll find specific low-mileage operation intervals. In addition to these model-specific guidelines, here’s a handy checklist for all hypcars:

Develop a habit of frequently checking underneath the car for hydraulic leaks. If you spot any, locate the source and tackle it right away before they become many!
Keep a close eye on the car’s ride height to ensure it remains consistent. While an experienced eye can give you a rough estimate, precise measurements from the anti-roll bar to the ground will provide accuracy.
Regularly check the levels of engine oil, transmission oil, coolant, and hydropneumatic fluid. Always adhere to the recommended mileage and fluid types, especially for automatic gearboxes.
Check the tyre pressure every two months and rotate the tyres every 10 000 km. Remember, the maximum lifespan of any tyre is about 10 years.
Inspect the battery terminals for corrosion and clean them as needed. Be sure to replace the battery every 5 to 7 years.
Clean the interior regularly to prevent dirt and dust build-up. This is also an excellent opportunity to inspect and, if necessary, repair or replace the upholstery.
Clean the windscreen and windows, and check the condition of the wipers at the start of the rainy season.
Wax the car once a year and polish as necessary.

A quick word on fuel. If you’re fortunate enough to own a hypcar manufactured before 1987, you’ll want to stick with E5 petrol, preferably with an octane rating of more than 95. Why? Well, E10 petrol, with its higher ethanol biofuel content, could lead to corrosion in the metal, plastic, and rubber components of your fuel system over time. For those with newer engines, you can try E10 in a pinch, but it’s best to avoid it, especially if you drive your car infrequently.

Now, let’s talk about the biggest enemy of hydropneumatic components: prolonged inactivity! Those rubber seals and hoses, along with their plastic connectors, can deteriorate quickly when not in use. We’re talking about drying out, hardening, and eventually cracking and leaking. If you notice any rubber hoses on the verge of failure, it’s advisable to replace them before it becomes a bigger issue. Hypcars from before the 1980s are particularly prone to high-pressure pipe leaks. These hydraulic lines can stretch over 50 metres and are susceptible to metal fatigue, especially if they are not securely fastened to minimise annoying vibrations.

Take the DS semi-automatic models, for instance: their intricate circuits can be somewhat temperamental. The SM, too, has its own hydraulic complexities. On the flip side, models like the ID and GS/GSA are relatively simpler since they skip power steering. If you’ve got a later model, like the XM, you might find them more reliable thanks to enhanced materials, but even these can develop hardened—and ultimately cracked—rubber hoses and plastic connectors as they reach the 30-year mark. Watch out too for the octopus-like junction hoses and the return Rilsan pipe connectors in the 1980s and 1990s models; they can harden and break, so regular checks are definitely essential!

As soon as you get your hands on a hypcar, make sure to renew the LHM fluid and clean or replace the filter. And don’t forget to check the sphere pressure every four years at a specialised workshop. Over time, the compressed nitrogen in the spheres can dwindle, leading to a harsher ride without sacrificing road-holding. If you have older sphere models (pre-1975), you’re in luck: they can be serviced by replacing the diaphragm and refilling. However, those welded sphere models can only be refilled once before needing to be replaced. For more tips and tricks, check out the BX Project for insights on sourcing those elusive hydropneumatic spheres.

If you encounter any issues with your hydropneumatic components, it’s crucial to tackle them head-on by replacing the damaged parts with top-notch replacements—ideally, a NOS (new old stock) piece or a high-quality refabricated option. Cutting corners here could lead to bigger bills later and might put your ride quality and safety on the line. This advice also applies to all mechanical components tied to your car’s safety, such as the steering, braking, and suspension systems. And remember, when it comes to body parts and trim, always select parts that are right for your specific model! While there are numerous online shops that focus on spare parts for particular models, platforms like the Classic Parts Finder can help you track down or sell parts for nearly any classic car.

It’s worth mentioning that, contrary to popular belief, finding spare parts for older hypcars isn’t always a daunting or expensive task. For example, sourcing parts for the CX and XM models can be significantly trickier than for the iconic DS. This predicament largely stems from Citroën’s infamous lack of support for its older models, a stark contrast to brands like Rolls-Royce and Mercedes. While there’s no one-size-fits-all trend, it’s often noted that as models age, their parts prices can increase—sometimes even exponentially! Interestingly, spare parts for the DS are now more affordable and accessible than they were 30 years ago, thanks to rising demand and the early cessation of Citroën’s official supply.

Like all classic cars, hypcars may need a full or partial respray, with a strong focus on preserving their original colour. When it’s time for a fresh coat, keep a couple of key factors in mind. First, don’t skimp on the quality of materials (including primer, paint, and varnish), as these directly influence the appearance and durability of the finish. Second, always ask for a paint sample before diving in. This is critical for two reasons: in a partial respray, the original colour may have faded over time, leading to a possible mismatch with the new paint. You may need a spectrometer or a thorough visual check to ensure everything lines up perfectly. Even in a full respray, the colour code may not be accurately represented in the paint, as modern formulations can differ from the originals, requiring tweaks for the best result. It’s also worth noting that an expert’s partial or local respray can yield results just as impressive as a complete paint job. In the video above, auto body repairer Kostas skillfully showcases this process, achieving remarkable outcomes.

Restoring or refurbishing a classic car to its original glory while also preserving its legacy is often the main goal of car enthusiasts. Whether it’s through retrofitting or restomod modifications, the choices ultimately hinge on the owner’s personal taste, with various aspects explored in “The Future of Hypcars.” One thrilling retrofit we’ve implemented in our hypcars is the upgrade of insulation materials alongside modern lighting and sound systems. These tweaks are non-invasive, easily reversible, and keep the historic character of the vehicles intact. A subtle resto-mod enhancement we regularly apply is upgrading the lighting with contemporary LED or Xenon bulbs. This adjustment maintains the car’s authenticity while significantly improving safety and driving comfort.

One last point on valuing classic cars is that they are seen as true collectors’ gems when they come with complete folders of preserved manuals and documents. Owning and maintaining authentic paperwork (such as bills of sale, car titles, and certificates of conformity), along with maintenance records and photos or videos of major repairs, helps to document your hypcar’s history and boosts its value for future sales. Thanks to digital preservation technology, classic car enthusiasts can easily digitise the documents and histories of their beloved vehicles. You can find more information on digital preservation here: “Fédération Internationale des Véhicules Anciens.”

Long Immobilisation

When we refer to “immobilisation,” we mean the period commonly known as hibernation in many countries. This phase should typically last no longer than 3 to 4 months. If you need to store your classic car for an extended period, investing in monitored professional storage facilities is advisable. Proper storage is crucial to prevent deterioration; the space should be covered, dry, well-ventilated, and ideally humidity- and temperature-controlled to ward off rust and mould.

Here are some tips for keeping your hypcar(s) in top shape during prolonged inactivity:

Give your car a thorough cleaning inside and out, and treat rubber trims with silicone or Vaseline for added shine and protection.
Fill the fuel tank to prevent condensation, which can lead to corrosion (note: this does not apply to hypcars with a plastic tank, e.g., Citroen SM).
Although not compulsory, it’s a good idea to change the oil.
Increase tyre pressure and consider using special tyre cushions to minimise deformation; alternatively, lift the car.
Set the hypcar to its lowest suspension position to relieve pressure in the hydropneumatic system.
Avoid engaging the handbrake to prevent unnecessary tension on the mechanism and to stop the pads from sticking to the discs.
Leave one or two windows slightly ajar for air circulation; just a few millimetres will suffice.
Disconnect the battery from the car and connect it to a battery maintainer.
Use a high-quality breathable cover instead of plastic.
Check your car’s condition regularly to ensure it remains in great shape. If possible, start the engine and raise and lower the suspension a few times.

When it comes to potential leaks, remember that hypcars are lively hydropneumatic marvels that seem to breathe, communicate, and even sweat! As long as you don’t spot any serious bleeding (high-pressure fluid leak) or incontinence due to age (significant fluid loss), just slipping a piece of cardboard under the engine compartment should suffice as a preventive measure.

Oh, and keep an eye out for pesky rodents! They’ve got a knack for nibbling on cables and hoses. And if you live in a busy area, your envious neighbours might pose an even bigger threat to your prized collectible. From personal experience, installing a surveillance camera is a smart move!

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Where Did All the Mechanics Go?

The hypcar collection brings together models from Citroën, British Leyland/Austin, Rolls-Royce, and Mercedes, each in various conditions at the time of acquisition. We have owned and curated some of these vehicles for over 50 years, aiming to preserve them in the best possible state for future generations. Regardless of their initial state, their current pristine condition, or the journey towards achieving it, is the result of meticulous care, supported by a handpicked network of experts.

Choosing a good mechanic for servicing and maintaining a hypcar is not just critical but can be trickier than for conventional classic cars. Even older vehicles, for instance, from the early days of motoring, have a more straightforward mechanical design that technicians can easily handle. In contrast, the hydropneumatic suspension, braking, steering, and, in some cases, gear changing demand experienced hands and specialised tools for repairs. Additionally, certain hypcars (e.g. the DS) come with unique bodywork configurations where fully detachable body panels must be adjusted to the millimetre during reassembly.

Nowadays, finding a mechanic with experience across all hypcar domains is becoming increasingly challenging. Most car technicians now focus more on electronic expertise rather than the mechanical or hydraulic skills associated with hypcars. Even auto body technicians tend to replace rather than repair body panels. Furthermore, as hypcars from the 1970s or earlier become increasingly longstanding, they start to develop new issues that were previously unheard of, often displaying warning signs that are tough to detect before a catastrophic breakdown occurs. Only an expert who experienced these cars when they were brand new can easily spot whether a rolling, mechanical, or aerodynamic sound is out of the ordinary and address it appropriately.

I vividly remember accompanying my father to Citroën’s authorised workshop for repairs or servicing during my teenage years. It was an exhilarating experience to watch those mechanics at work, diagnosing and discussing solutions to fix hypcars. Unusual noises and vibrations served as early indicators; any sound deviating from the norm—be it hissing, rattling, squeezing, coughing, or knocking—was carefully assessed and dealt with immediately. A correct diagnosis was always their top priority and often led to inventive, out-of-the-box solutions!

The last generation of skilled mechanics who worked on hypcars during their production era is now largely retired or nearing retirement, and they are certainly not getting any younger. This makes it challenging to find professionals specifically qualified in hydropneumatic systems, resulting in a rapid decline in this knowledge. It is now crucial to seize the last opportunity to pass on this expertise to the younger generation.

Therefore, we encourage young people to overcome their hesitations and dive into vintage restoration! Let’s celebrate and preserve the incredible wealth of knowledge held by the older generation of mechanics. Environmental concerns should take a back seat for these vehicles, as they no longer serve as a means of transport. Instead, they are valued as precious symbols of bold technological innovation and the ultimate expression of freedom in industrial design.