BMW debuted the iDrive 8 infotainment system and made minor exterior design modifications, including an optional carbon fibre roof, during the LCI of the BMW M340i xDrive in 2022. Under the hood, where the B58 resides, there was one more significant alteration. No, it’s not the turbocharged inline-six engine’s 382 horsepower and 500 Newton-meters (369 pound-feet) of torque from a 3.0-litre displacement.
We’re talking about a mild hybrid system. This system’s combustion engine receives support from a 48V starter-generator and a momentary 11-hp boost. In addition to giving the performance sedan more power, it also makes it more efficient. As demonstrated in a fuel consumption test, it enables engine-off coasting to conserve valuable gasoline.
Considering the standard start/stop functionality, the engine of this M340i was off for nearly half of the test while it ran. It took 53 minutes and 25 seconds to complete the drive with the M Performance 3 Series in Eco Pro driving mode. And during that time, the engine was off for an astounding 25 minutes and 20 seconds, or around 47% of the time. At an average speed of 24 kilometres per hour, the sports sedan travelled 21.8 kilometres (13.6 miles) (15 mph).
The trip computer recorded an average fuel consumption of 8 litres per 100 kilometres after the drive (29.4 mpg US or 35.3 mpg UK). After refuelling, the calculations revealed that fuel consumption was 2% higher. The M340i was tested in less than ideal circumstances. 2 degrees Celsius, or 28.4 degrees Fahrenheit—while mounted on winter tires in a congested city.
Even with its recently added mild-hybrid powertrain, the M340i is no Prius. Nevertheless, Toyota’s eco-hero is neither a luxury nor a high-performance sedan. The M340d, with its economical inline-six diesel, is another option for a more cost-effective M Performance 3 Series. Both M Lite versions are offered in the more useful Touring body style. This shows BMW’s continued commitment to serving a diverse customer base.