The BMW 633CSi, produced between 1979 and 1982, represents a pivotal point in the first generation (E24) 6 Series lineup. Positioned as a mid-range offering, it bridged the gap between the entry-level 630CS and the high-performance 635CSi. The 633CSi was designed to offer a blend of grand touring comfort and respectable performance, appealing to buyers seeking a sophisticated coupe experience. It was a key model for BMW in establishing the 6 Series as a premium, driver-focused vehicle in the North American and European markets.
Technical Specifications
| Brand | BMW |
| Model | 6 Series |
| Generation | 6 Series (E24) |
| Type (Engine) | 633CSi (197 Hp) |
| Start of production | 1979 |
| End of production | 1982 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Coupe |
| Seats | 4 |
| Doors | 2 |
| Fuel consumption (economy) – urban | 16.9 l/100 km (13.9 US mpg, 16.7 UK mpg, 5.9 km/l) |
| Fuel consumption (economy) – extra urban | 7.7 l/100 km (30.5 US mpg, 36.7 UK mpg, 13 km/l) |
| Fuel consumption (economy) – combined | 11.5 l/100 km (20.5 US mpg, 24.6 UK mpg, 8.7 km/l) |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 7.9 sec |
| Acceleration 0 – 62 mph | 7.9 sec |
| Acceleration 0 – 60 mph | 7.5 sec |
| Maximum speed | 215 km/h (133.59 mph) |
| Weight-to-power ratio | 7.5 kg/Hp, 134 Hp/tonne |
| Weight-to-torque ratio | 5.2 kg/Nm, 193.9 Nm/tonne |
| Power | 197 Hp @ 5500 rpm |
| Power per litre | 61.4 Hp/l |
| Torque | 285 Nm @ 4300 rpm (210.21 lb.-ft. @ 4300 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | M30B32 |
| Engine displacement | 3210 cm3 (195.89 cu. in.) |
| Number of cylinders | 6 |
| Engine configuration | Inline |
| Cylinder Bore | 89 mm (3.5 in.) |
| Piston Stroke | 86 mm (3.39 in.) |
| Compression ratio | 9.3:1 |
| Number of valves per cylinder | 2 |
| Fuel injection system | Multi-port manifold injection |
| Engine aspiration | Naturally aspirated engine |
| Engine oil capacity | 5.8 l (6.13 US qt | 5.1 UK qt) |
| Kerb Weight | 1470 kg (3240.8 lbs.) |
| Max. weight | 1830 kg (4034.46 lbs.) |
| Max load | 360 kg (793.66 lbs.) |
| Trunk (boot) space – minimum | 415 l (14.66 cu. ft.) |
| Fuel tank capacity | 70 l (18.49 US gal | 15.4 UK gal) |
| Permitted trailer load with brakes (12%) | 1800 kg (3968.32 lbs.) |
| Length | 4755 mm (187.2 in.) |
| Width | 1725 mm (67.91 in.) |
| Height | 1365 mm (53.74 in.) |
| Wheelbase | 2626 mm (103.39 in.) |
| Front track | 1422 mm (55.98 in.) |
| Rear (Back) track | 1487 mm (58.54 in.) |
| Drag coefficient (Cd) | 0.41 |
| Minimum turning circle (turning diameter) | 11.2 m (36.75 ft.) |
| Drivetrain Architecture | The Internal combustion engine (ICE) drives the rear wheels of the vehicle. |
| Drive wheel | Rear wheel drive |
| Number of gears and type of gearbox | 4 gears, manual transmission /5 |
| Front suspension | Independent, type McPherson with coil spring and anti-roll bar |
| Rear suspension | Independent coil spring |
| Front brakes | Ventilated discs |
| Rear brakes | Disc |
| Steering type | Worm-reduction unit |
| Tires size | 195/70 R14 |
| Wheel rims size | 14 |
Powertrain & Engine Architecture
The heart of the 633CSi is the M30B32 engine, a 3.2-liter inline-six cylinder powerplant. This engine, a descendant of BMW’s long-running M30 family, featured a cast iron block and an aluminum cylinder head. It utilized Bosch L-Jetronic fuel injection, a sophisticated system for its time, delivering precise fuel metering for improved efficiency and performance. The engine boasted a 9.3:1 compression ratio and employed a single overhead camshaft (SOHC) valvetrain with two valves per cylinder. The M30B32 produced 197 horsepower at 5,500 rpm and 285 Nm (210 lb-ft) of torque at 4,300 rpm. The 633CSi was typically offered with a 4-speed manual transmission, though a 5-speed manual and a 3-speed automatic were also available. The automatic transmission, a ZF 3HP22, was geared towards providing smooth, comfortable shifts rather than outright performance.
Driving Characteristics
The 633CSi with the automatic transmission offered a relaxed and refined driving experience. While not as overtly sporty as the 635CSi, it provided ample power for comfortable highway cruising and spirited backroad driving. The automatic transmission, while smooth, did detract somewhat from the car’s overall responsiveness. Gear ratios were optimized for fuel economy and ease of use, resulting in slightly slower acceleration compared to the manual versions. The 0-60 mph time was around 7.5 seconds, respectable for the era, but noticeably slower than the manual equipped models. The car’s weight distribution, favoring the front end, contributed to predictable handling, though it wasn’t as nimble as some of its rear-wheel-drive competitors.
Equipment & Trim Levels
The 633CSi came reasonably well-equipped as standard. Interior appointments included cloth upholstery, power windows, and central locking. Leather upholstery was a popular optional extra, along with a sunroof, air conditioning, and upgraded sound systems. The dashboard layout was typical of BMWs of the period, featuring a driver-focused design with clearly marked gauges. Trim levels were relatively simple; options were generally selected à la carte, allowing buyers to customize their vehicle to their preferences. The 633CSi aimed for a balance between luxury and sportiness, offering a more comfortable and refined interior than the base 630CS.
Chassis & Braking
The E24 6 Series utilized a robust chassis with independent suspension all around. The front suspension employed McPherson struts with coil springs and an anti-roll bar, while the rear featured an independent semi-trailing arm suspension with coil springs. The 633CSi was equipped with ventilated disc brakes at the front and solid disc brakes at the rear, providing adequate stopping power for its weight and performance. Steering was via a worm-reduction unit, offering a relatively direct feel, though it lacked the precision of more modern steering systems. The car rode on 14-inch wheels with 195/70 R14 tires.
Market Reception & Comparison
The 633CSi was generally well-received by automotive critics. It was praised for its comfortable ride, refined interior, and capable engine. However, some reviewers noted that the automatic transmission dulled the driving experience compared to the manual versions. Compared to the 630CS, the 633CSi offered a significant performance upgrade, while remaining more affordable than the flagship 635CSi. Fuel economy was reasonable for the time, averaging around 20.5 mpg combined, but was still relatively high compared to more modern vehicles. Reliability was generally good, though maintenance costs could be substantial due to the car’s complex engineering.
Legacy
The BMW 633CSi remains a sought-after classic car today. The M30B32 engine is known for its durability and relatively straightforward maintenance, although parts availability can be a challenge. Well-maintained examples command a premium in the used car market. The 633CSi represents a sweet spot in the E24 lineup, offering a blend of performance, comfort, and style that continues to appeal to enthusiasts. It’s a testament to BMW’s engineering prowess and a reminder of a time when grand touring coupes were built to be driven and enjoyed.
