My 2010 X5M with 37,000km/23,000 miles has recently shown a similar problem. When this first happened, the engine started normally after sitting outside overnight in freezing weather. Pulling out of the driveway, there was a very noticeable lack of power. There was no misfiring, and when stopped, the engine seemed to idle okay at the usual 500rpm.

Despite flooring the accelerator, the engine revs would climb very slowly. It was not possible to get a kickdown downshift. Beyond a small amount of accelerator depression it felt almost as if there was no additional fuel was being delivered to the engine (just the ‘feeling’—no indication that the fuel supply had anything to do with the root cause of the problem). Shifting the transmission into ‘Sport’ mode, or shifting gears manually, shifting in and out of ‘M’ mode, or changing DSC and MDM settings made no difference.

About three hours later, after a complete cool-down, I made a 10km/6mi expressway trip at 120kph/70mph. No change. Just no power.
A yellow ‘exhaust gas values’ alarm had appeared. Probably from unburned gasoline getting into the catalytic converter sensors, due to the malfunctioning engine. Other than the ‘exhaust gas values’ notification, there were no other alarms or notifications.
Speculating that the cold weather might be a factor, the next day I garaged the vehicle and left it to warm up at 65°F/18°C. A few hours later, I started it up. Problem gone—the vehicle was driving normally. During the brief drive, the ‘exhaust gas values’ alarm cleared itself—not unusual, based on previous experience...

About 10 days later, again in ~0°C/32°F weather, the problem recurred. The engine started normally, but on the highway, the power was low. It didn’t seem as bad as the first time, but notionally the power seemed to be down by perhaps one third to one half, or so. As before, changing the engine and transmission settings had no effect,. Low power persisted for a ~10km/6mi highway trip. Fuel level was low, and speculating that the problem might be fuel-related, I stopped and gassed up. On start-up, the problem was gone. This time, there were no alarms or warning indicators of any kind.
About three weeks after the first occurrence, the vehicle was checked out by the dealer (Otto’s, in Ottawa, Canada). The rather sparse details on their diagnosis and correction from the invoice are shown below; I have requested a complete list of the fault codes that were found—but these have not yet been provided.

COMPLAINT: ENGINE SEEMS BEYOND SLUGGISH. BARELY ANY POWER.
CAUSE: COOLANT LOW. NO LEAKS FOUND. CAN AFFECT PERFORMANCE IN ENGINE WHEN LOW COOLANT IS DETECTED.
CORRECTION: SCANNED FAULTS, FOUND FAULTS FOR CHARGE AIR, COOLING SYS. REDUCED PERFORMANCE OPERATION DUE TO COOLANT LOSS ON PUMP 1 AND 2 THAT WAS DETECTED.
. RAN TEST PLAN, CHECKED FOR LEAKS. NONE FOUND.
. TOPPED UP COOLANT ON BOTH RESERVOIRS. RAN PUMP, BLEED SYS. FOUND COOLANT TOO LOW. REQUIRED 1 TO 1.5 LITERS OF COOLANT.
. CLEARED FAULTS. ROAD TEST OK.
. ALSO FOUND FAULT 2A7A CAMSHAFT POSITION CONTROLLER, EXHAUST COLD START. HAPPED FOUR TIMES IN 2000KMS.
. RAN TEST PLAN FOR VANOS SOLENOIDS. PURGED SOLENOID VALVES. NO FAULTS FOUND 01130 00000000 03 901.

The problem reappeared less than a week after the dealer ‘correction’. After a 500km/300mi trouble-free highway trip, the syndrome recurred the next day, after a normal startup. The power loss was very noticeable, but probably not as severe as the first time. I immediately stopped and restarted—and the problem cleared itself.

A posting on Xoutpost by Member ///MB, and the referenced video describe my experience exactly: http://www.xoutpost.com/bmw-sav-foru...oss-power.html