BMW Buyer's Guide
BMW's auction market is a pyramid with M cars at the top and a very broad, very affordable base. Our 56 tracked sales run from £430 for a tired 3 Series to £77,063 for an M3, and the shape in between is consistent: the badge on the bootlid matters more than the age of the car.
The story, briefly
The company built its modern reputation on one formula: a smooth straight six driving the rear wheels in a compact body. The 2002 established it, the 3 Series industrialised it, and the M division (founded 1972) weaponised it, starting with homologation specials like the E30 M3. Build quality through the eighties and nineties was genuinely exceptional, which is why so many high-mileage examples survive and why the good ones make such strong keepers.
Which BMW, for what money
M money. Twenty-three 3 Series sales span £430 to £77,063, median £9,563; the top quarter of that range is all M3, and generation matters more than condition at the margin. August underlined it: an E46 M3 Individual manual made £33,750 and an E36 M3 saloon £24,188, the latter a strong result for the generation that usually lags E30 and E46. Five 5 Series sales carry a median of £16,875, M5s at the top, though a 2014 F10 M5 at £14,333 shows the modern V8 cars are still depreciating rather than appreciating.
Enthusiast money. Five 6 Series sales made £3,420 to £15,188, median £7,475: the E24 shark-nose coupé remains one of the more undervalued grand tourers of its era, with most mechanical parts shared with the contemporary 5 Series. Ordinary E30, E36 and E46 coupés and saloons in the £2,000 to £8,000 band are the volume of our records. The oddities now have data too: a 1991 Z1 brought £23,400, and two Isettas made £6,750 and £11,813 in a single August weekend.
Speculative money. Fourteen Z3s sold between £890 and £27,250, median £3,250. The four- and six-cylinder roadsters at the bottom of the range are cheap, plentiful and mechanically long-lived; the M roadsters and coupés at the top have already been collected, and a £25,875 Alpina Roadster S this August says the special Z4s are following them. A £3,250 Z3 with history is one of the better value-per-mile propositions in our entire dataset.
What goes wrong
Cooling systems, first: plastic radiators, expansion tanks and water pumps on nineties and 2000s cars fail on age and take head gaskets with them when ignored. Rear subframe mounting points crack on hard-used E36 and E46 cars; check for repairs. Rust attacks arches and sills from the E30 backwards. VANOS units rattle but rarely fail terminally. Parts supply is excellent across every era, including remanufactured trim through BMW Classic, and the specialist network is deep.
Our view
Buy on the straight six. An E46 330Ci, an E39 528i or a six-cylinder Z3 costs £3,000 to £8,000 at auction, runs to 250,000 miles with cooling-system maintenance, and has the club and parts infrastructure of a much more expensive classic. Treat sub-£1,000 cars as parts donors, and treat any M car without a complete history file as the seller's problem, not yours.