Citroen used to build bonkers cars and while some loved the company for it, most buyers stayed away, petrified of the complex hydraulics and crazy interiors. What the company needed, if it wasn't going to go belly up, was a more mainstream model with just the right amount of individuality, but not so much that potential buyers were scared.
The BX was that car. It looked like nothing else on the road, yet the engineering was largely conventional. Designed by Bertone and borrowing most of its running gear from the Peugeot parts bin, the BX doubled Citroen's UK sales. If Q cars float your boat, too (that's Q for quick), the BX GTi 16V could be the classic you've been searching for.
WHAT TO LOOK FOR
BODYWORK
Forget the seemingly complex mechanicals; rust is what kills BXs. Plastic panels (some bonnets, all tailgates and fuel filler flaps) can allow cruddy BXs to look decent - while the structure underneath is compromised.
Front wings tend to last; they're easily replaced anyway, as they bolt on, and used ones are plentiful. Rear quarter panels are less durable, especially on estates that were built (but poorly rustproofed) by Heuliez. Replacement panels are scarce and repairs involve welding. Check the front inner wings where they meet the wheel housing; rust here is common and it's not easy to fix on cars with ABS, as the pump is on the nearside inner wing. Also check under the airbox; effective repairs entail removal of the wing and wheelarch liner to gain access. Look for rust stains in the seam sealer between wheel tub and inner wing; also inspect the windscreen surround for bubbles and previous repairs. Many BXs have had new windscreens and poor fitment leads to rust.
Door hinges can break away from the A-post when the welds give way. Repairs are possible, but a pain. If the hinge flexes as the door is opened and closed, the A-post is probably rotten. Check the top of the A-post above and behind the hinges as these can rust through.
The rear door shuts and wing rot because water and mud collect behind the rear wheel spat so it corrodes out of sight. Rust around the sunroof is rare, but check anyway, as it's difficult to repair; most hatchbacks have an electric tilt/slide sunroof, but estates weren't offered with one. Some have been sealed up because of blocked drain holes; they're at each corner of the mechanism, and clearing is fiddly, but possible. Check for damp around the aperture.
The plastic bumpers age badly but they're easy to remove and replace. Most are colour-keyed and they fade, but can be rejuvenated with a hot air gun, bumper gel or fresh paint. 16-valve models got their own bumpers that are fragile and scarce.
ENGINES
Engine-wise, there's not much to worry about. Most surviving BXs feature a 1769cc or 1905cc naturally aspirated or turbocharged XUD diesel engine, as fitted to ious PSA and Rover models. The XUD unit lasts forever if looked after, although head gaskets can fail - but the engine will still often keep working for ages. Changing the oil every 6000 miles, the coolant every two years and the cam belt/water pump every 40,000 miles (or four years) will see 200,000 miles despatched with ease. All engines have a cambelt apart from the early 1.4-litre petrol unit.
Petrol fans could choose between a 1.4 carburetted or 1.6/1.9 XU petrol in carb or injected forms. Until 1988 the 1.4 was the gearbox-in-sump unit shared with the Visa and early 205/309; later came the more modern TU unit shared with the Peugeot 106 and Citroen Saxo. The later unit is more refined and parts supply is better. Both give nippy performance, but are low geared, so they're vocal on motorways.
The .6 and 1.9 XU engine came in four-speed auto or five-speed manual forms with 80-160bhp, the latter in twin-cam Mi16 form. This engine is reliable if maintained, but carb versions go out of tune and the automatic choke on twin-choke Solexes can be unreliable. Overhaul kits and manual choke conversions are available, but the best fix is to fit more reliable Weber replacements - although sometimes the system just needs tuning.
The final cars got electronic fuel injection and catalytic converters, which rarely give problems, although air intake leaks can cause rough running and idling issues on cars with multipoint injection.
TRANSMISSIONS
Gearboxes are tough. Some basic 1.4-litre BXs got a four-speed box, but all others got five speeds; entry-level 1.4-litre cars are almost extinct now. The same BE1 or BE3 gearbox was used across the range - the two are interchangeable. Also fitted to the Peugeot 309 and 405, decent used transmissions cost £50-£100, but you're unlikely to need one. The thing likely to wear is the idler gear, which gets noisy. However, the selector mechanism and linkages can wear, but they're cheap to replace. Clutches can last 200,000 miles; as they wear they get sticky and stiff. However, these symptoms can also betray a tired clutch cable; replacements are cheap, readily available and easy to fit.
Clutch cables can also snap, while a stiff pedal can be greatly improved by lubricating teh lever on top of the bell housing. Speedo cables fail regularly but they're no longer available. They're long and run through the offside of the bulkhead and behind the dash at a sharp angle. If the speedo is wobbly or ticking, the cable is on its way out and you'll probably have to get one made specially. Automatic BXs are common and they're unbreakable if the fluid is changed correctly. Dextron 2 needs to go in, but Dextron 4 is often used - which destroys the transmission. Decent used auto boxes start at £100.
STEERING AND SUSPENSION
Most BXs have had a suspension overhaul by now. A hard, bouncy ride betrays worn spheres; they're typically cheaper than a shock absorber and can be replaced in minutes. If the rear wheels lean in at the top and there's creaking or cracking, the rear arm bearings have worn. Budget £150 per side to get them fixed. Suspension struts rarely fail (but the rubber return pipes do), although they become stiff and sticky and can groan when raised to full height. They can be lubricated, but replacement is better, although new ones are pricey at £300 (if available at all). Reconditioned items are £150 apiece on an exchange basis. A BX will settle down to its bump stops over a few hours when switched off, as hydraulic pressure drops. When started it should raise itself back up to normal height within 5-10 seconds; any longer indicates a tired pump and/or accumulator sphere, as does stiff or sticky steering or the low pressure light coming on. Both are available and are easy to fit. Finally, check for hydraulic leaks, which are obvious as the LHM fluid is bright green. Later models had coated hydraulic pipes, but the earlier steel ones fatigue and corrode; if they fail there'll be no suspension, brakes or power steering. You have been warned!
WHEELS AND BRAKES
The braking system is largely conventional in its design, with no inherent weaknesses. Everything is available and nothing is costly. Handbrake cables can seize, but they're easily freed up. On cars with ABS, make sure the warning lamp illuminates then extinguishes when the engine is started; new sensors are extinct, so you'd have to remove the system to avoid and MoT failure, or find a decent used sensor.
TRIM AND ELECTRICS
There were two basic seat styles. The softer, more sculpted standard seat that's normally covered in a tweed or herringbone fabric can wear through, especially on the driver's side. A sportier design was fitted to the GTi 8v and TZD Turbo; these were fitted to most models evenutally. The 160bhp 16-valve models got bespoke front seats with lumbar support that are supremely comfortable and supportive, but as rare as the 16v itself. Electrics can also be temperamental. Fan motors pack in (usually because of a dodgy earth) while heater controls can seize. Forcing them breaks them; replacements are available, but fitment is fiddly as they're behind the dash. The spindle wears in the single front wiper. Decent used replacements are scarce, so it's best to fit new bushes.
VERDICT
Why do you want one? You don't want to follow the crowd, and while the contemporary alternatives are no longer mainstream, they still lack the left-field appeal of the Citroen. However, despite its reputation, the most unusual thing about the BX is its styling; the engineering itself is relatively conventional, aside from that hydropneumatic suspension. Speaking of which, it's one of the major attractions of the BX, not a reason to run away in terror. It's reliable and endows the Citroen with a balance of ride and handling that you just can't achieve with conventional steel springing.
If you're thinking of buying a left-field classic that's eminently usable and cheap to run, the BX fits the bill. But the survival rate is poor, which is why you're unlikely to see another at a show. Most of the cars left are Mk2s (introduced in 1986) and diesel-powered; find one with a good history and you've got an ultra-practical classic. Tattycars can be bought for just a few hundred quid, while even the best examples command little more than £2000. That's top value in any language.