Unlike most PHEVs, the BMW XM doesn't have a mode to charge the battery with the engine.
CarBuzz recently had a chance to experience the 2023 BMW XM at the global launch event, and although we can't talk about how it drives just yet, we did learn that it's missing an important feature that's common on most plug-in hybrids: the ability to charge the battery with the engine.
Using the M Hybrid button on the center console, drivers can select from three different modes: Hybrid, Electric, and eControl. Hybrid and Electric are self-explanatory; the former combines the electric motor and gasoline engine, while the latter shuts off the engine and runs on electricity only for around 30 miles. These are no different than other PHEVs.
BMW's eControl mode is where things start to diverge from the norm. Whereas other PHEVs we've driven provide an option to hold the state of charge or use the engine to generate more electricity into the batter, the XM can only do the former.
When asked why there is no charge option, a BMW spokesperson confirmed "it would simply kill the fuel economy," citing that "running the engine to charge the battery is inefficient."
BMW is not wrong here, as running the engine in a PHEV to charge up the battery does severely hurt fuel economy. Basic physics says using the engine to run the car would be more efficient, only plugging in when you can to refill the battery. Automakers typically still offer this feature so owners can end up with a full battery at the end of a long highway stint and enjoy electric-only driving when they reach their destination, but it's unclear how many people take advantage of this option.
Though the XM can't use its engine to charge the battery, it can recoup energy from the brakes or coasting with two regeneration settings: Normal and Max. Theoretically, the XM could replenish state of charge (SOC) with spirited driving, especially if it's downhill. This is perhaps the one place where its insane weight (6,063 lbs) comes in handy, as the momentum it carries downhill can put some serious energy back into the motors and batteries.
The XM is not the first BMW PHEV to lack a recharge on-the-go feature. Other models like the X5 Hybrid and the X2 Hybrid (not sold in the US) only offer an option to hold the state of charge, not increase it. "It would hurt our fuel economy ratings if we offered that feature," the spokesperson said.
There could be some truth to that as Hyundai Motor Group PHEVs used to offer an option to charge while driving, but no longer has it. The Audi Q5 PHEV has both a charge mode and a charge hold mode, as do Toyota and Volvo models, so some automakers are still able to have it. But those automakers' PHEVs aren't running 4.4-liter twin-turbo V8s, and that's the biggest difference.
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