Precision engineering and operational efficiency are two traits which are inextricably linked with German automobile production, and with BMW especially. While there have been countless models which justify the marque’s reputation for fast, well-engineered and luxurious cars, surely one of the best there has ever been is the M635CSi.

Introduced in 1976, the E24 was the first incarnation of BMW’s 6 Series of handsome grand-touring coupés, an exceptionally stylish creation by Paul Bracq with crisp, incisive shark-nosed looks and a range of puissant overhead-cam six-cylinder engines.

From 1978, the flagship of the 6 Series line was the 635CSi. Following a facelift across the range in 1982, it gained the 3.4-litre M30B34 engine, which produced 215 bhp. By itself, it made for a thoroughly covetable car, but the best was yet to come. At the 1983 Frankfurt Motor Show, BMW excelled itself by bringing into the world the M635CSi, the last word in luxury and power.

‘M’, of course, stands for ‘Motorsport’, and what it meant for the 6 Series was the installation of the 3½-litre M88/3 dohc six, with Bosch Motronic fuel injection, a 10.5 to one compression ratio and power output of 282 bhp. 

Though the other 6 Series models were built with an emphasis on luxury and comfort, and hence were mostly fitted with automatic gearboxes, the M635CSi was very much conceived as a car for the driving enthusiast, and was accordingly equipped with a five-speed Getrag 280 manual gearbox.

Doubtless, that all sounds great on paper, but what does it amount to in the real world? Well, a 0-60 mph acceleration time of 5.8 seconds was jolly impressive, and so too was an overall top speed of 158 mph, which made the M635CSi the second-fastest BMW ever built after the M1.

Naturally, it came at a price – the difference between a well-specified 635CSi and its M-badged counterpart was roughly equal to the average British house price at the time – which has only served to make it more exclusive today. Only 5855 M635CSis were built from 1983 to 1989, so this is a rare opportunity to acquire the ultimate ’80s sports saloon.

This Luton-registered BMW’s history can be traced back to 2005, when it was sold through Birds, the well-known BMW tuning company, to a Mr. Frederick Holmstrom of Lockerbie. In 2007, after it had covered 68,000 miles, the car was placed on SORN and then sold to Mr. John Hogarth of Suffolk.

Mr. Hogarth subsequently commenced a full, no-expense-spared restoration of the car over a period of four years, the project finally being completed in 2013. Much of the work was undertaken by Somerset-based classic BMW specialist Fritz’s Bits.

Sadly, Mr. Hogarth passed away not long after the restoration was finished, hence the BMW has received very little use. Following his passing, the car was retained by his family, who have decided that it really needs to go to someone who will use and enjoy it just as Mr. Hogarth intended.

The M635CSi comes with two vast files of paperwork, including a copious quantity of invoices for parts and services issued between 2005 and 2013. Many of these detail the work undertaken by Fritz’s Bits, and examination of the invoices will reveal just how Mr. Hogarth came to spend around £100,000 restoring the car.

The file also contains a number of MoT certificates issued between 1993 and 2007, plus one from 2020 and a current certificate valid until 20th September. Assorted other documents pertain to technical subjects, and there are a lot of sheets in particular detailing the BMW’s electrics and computer systems.

The BMW’s interior is utterly splendid, with much to appreciate and very little to fault. The black leather upholstery looks to be original and very well-preserved, having mellowed a bit with age but showing no signs of wear save for the inviting creases which beckon one to slide behind the wheel and sink into the firm but absorbent seats. The rear seats are especially good, and show very little evidence of past use.

The car’s carpets are clean and tidy and the dash and centre console are both exemplary. Despite the plethora of switches and buttons all requesting the driver’s attention, the fascia has barely acquired so much as the smallest mark over the past 37 years. 

The fascia itself is a prime example of smart yet attractive design, with all the little luxuries one is ever likely to want presented in a simple and uncluttered fashion.

There is some very light cosmetic wear around the rim of the steering wheel, and the doors are close to immaculate, although the plastic has picked up some light marks.

The headlining is near faultless, save for one or two marks which we think would should disappear easily with a good valet. The boot is wonderfully clean, with the floor in a beautiful state of presentation, and contains the original BMW first-aid kit and the spare wheel, which is in excellent condition.

Exquisite, superb and exceptional are all words which might adequately describe the Polaris Silver paint on this BMW. The car’s repaint during its restoration was evidently completed to an extremely high standard and, since the car has received such little use over the past 10 years, it has survived extremely well.

The brightwork is in similarly fine fettle, with the chrome bumpers sporting quite a spectacular mirror-finish, and the wheels, too, are in the most astoundingly good condition. 

Purists, of course, may grumble about Alpina wheels being fitted to a non-Alpina car, but it is generally considered that the Alpina wheels contribute towards superior handling and are also much easier to source than the original wheels. A spare set of Alpina wheels in equally good condition is also to be sold with the car.

It will be noted that there are some scratches on the car’s windows and on the rear light lenses, while there are some hairline cracks in the plastic of the rear spoiler, but aside from them the car is almost impossible to fault.

The car benefitted from a lot of welding during its restoration, which means that it is every bit as solid and sound underneath as it ought to be. With so few miles covered post-restoration, the floorpan, chassis rails and wheel arches are all still very clean, and have nothing to hide.

The BMW’s bonnet raises to reveal the most magnificent power-plant, beautifully presented. The 3½-litre fuel-injected straight-six really fills the engine bay, and both the engine and bay are themselves extremely clean.

It fires up on command, idles purposefully and, once warmed up, is a delight to take onto the road. At 37 years old, the M635CSi has performance capabilities that many modern cars would envy, and even a light touch on the accelerator is sufficient to feel yourself thrown back in your seat. This car is in excellent health and will certainly prove more than satisfying to the spirited driver.

Everything else appears to be in equally good order. The gearbox takes fast changes in its stride and the brakes operate with a reassuring firmness. Since it passed its latest MoT with no advisories, we are satisfied that everything is in order from a safety perspective.

You might notice the long line of 3 Series fleet cars parading up and down the M1, in and out of Watford Gap, and think to yourself ‘BMW. The Ultimate Driving Machine. Really?’ 

Well, in that context, probably not, but the slogan was coined back in the late ’70s, when BMW was still giddily breathing in the vapours of its well-publicised successes in the European Touring Car Championship with the 3.0 CSL and was busily preparing a radical mid-engined supercar, the M1, which would storm Le Mans.

To many enthusiasts, the period from the late ’70s to the early ’90s was something of a golden age for BMW, when its image was defined by its motorsports successes and the badge was something to aspire towards because it had connotations of quality, rather than mere status. 

Being more affordable and more prevalent in touring-car racing, the E30 M3 is probably the best-remembered BMW of the 1980s, but the car to have, if you could afford it, was undoubtedly the M635CSi. A better blend of performance and luxury is difficult to imagine, and it also happens to be extraordinarily good-looking. This, surely, is the car for which ‘The Ultimate Driving Machine’ was conceived.

You’ll find it’s ideal for carrying your family around in style, but if you can ditch them for an afternoon you’ll also discover just what a joy it is when you’re out on the open road, alone with the mighty engine. With fewer than 6000 built, they don’t come up for sale often and when they do, they’re not often as nice as this one. Truly, it’s an opportunity not to be missed.