BMW M3 (E9x) Buying Guide: Powertrain


The 3,999cc V8 engine used in all M3 models is an all-aluminium design that produces 420hp at 8,300rpm and 295lb ft of torque at 3,900rpm. BMW was very proud the engine also delivered 85% of its peak torque between 3,900rpm and its 8,400rpm red line, though this has not stopped many owners from complaining the engine can lack low-end shove for daily driving.

Get past 6K, then make the case for a C63
Get past 6K, then make the case for a C63
The engine returns an average of 22.8mpg yet drives the M3 from 0-62mph in 4.8 seconds with the six-speed manual gearbox. BMW went on to add its seven-speed Dual Clutch Transmission (DCT) soon after launch and that lowered the 0-62mph time to 4.6 seconds and has proved to be the more popular gearbox choice over the course of the E90 generation M3’s life. The Convertible deals with 0-62mph in 5.3 seconds and the saloon takes 4.9 seconds with a manual gearbox, while the DCT knocks 0.2 seconds off for each of these models.

BMW produced the M3’s all-alloy V8 at its Landshut foundry in Germany alongside the Formula One engines it was then supplying to Sauber. At 202kg in weight, the V8 was 15kg lighter than the previous E46 M3’s six-cylinder engine. Helping here was a one-piece forged crankshaft that weighed just 20kg. Induction was taken care of by BMW’s double VANOS variable valve timing, individual throttle butterflies for each cylinder and four valves per cylinder.

As part of the M3’s modern take on performance, it featured BMW’s EfficientDynamics technology. This used a smart alternator that could charge the battery as the car slowed or braked to recoup energy that would otherwise be lost.

420hp is made at 8,300rpm
420hp is made at 8,300rpm
At the rear, BMW employed an M Differential LSD that could send up to 100% of all power to a single wheel depending on available traction. There are also three engine map settings available to the M3 driver, which can be selected through the iDrive control and then the preferred one stored for immediate selection with the M Drive button on the steering wheel. This function can also be used to choose the driver’s ideal settings for the suspension and steering.

It’s worth checking these settings on any car you are viewing to buy as an indicator of what sort of driver the seller is, though many M3s simply have all settings wound up to maximum with the MDrive.

More importantly, check the car had its 1,000-mile service to remove the running-in fluids. This is vital with the M3 as missing this service can lead to permanent engine damage. Even so, the M3’s V8 motor will use around 250ml of oil every 1,000 miles, so don’t be surprised at this.

V8 should use 250ml of oil per 1,000 miles
V8 should use 250ml of oil per 1,000 miles
Checking the engine oil level, however, is trickier as there is no dipstick on the engine and you need to use the iDrive, which is not the most accurate at gauging oil level. Some owners report oil leaks from around the cam cover gasket, but this is rare.

There have also been some incidences of the fly by wire throttle going into limp mode, which can be solved by locking the car and leaving it for 15 mins to reset, but a permanent fix are new throttle actuators that will cost around £700 plus labour at a BMW dealer.

The differential can fail if a previous owner has abused the car, particularly on track days, so listen out for any rumbles from the rear of the car. Also at the back, many owners have opted for the OEM exhaust mode to remove some sound deadening material from the rear silencer and cover the perforated holes in the pipe. This gives the exhaust note a harder edged sound without it becoming boomy. Expect to pay around £200 for this.

There was a recall in late 2008 for the DCT gearbox as the control unit could be faulty and cause the engine to stall at low speeds. Check the service history of any car built between September and October 2008.


PHer's view:
My favourite part of car is the engine. The noise and power at the higher rev range makes it a really special car to drive. The lack of low down torque isn't much of an issue for me as I have the DCT gearbox so power is always on tap with a few clicks of the finger on the paddle shifters.
M Singh


Buying guide contents:
Introduction
Powertrain
Rolling Chassis
Body
Interior
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