this is another extreme example: http://www.bmwmoa.org/forum/showthread. ... el-mileage
MPG drops from 42-45 to 30-33 after replacing battery on a BMW. I didn't get a clear idea on how to solve the problem.

for example: http://repairpal.com/engine-stalling-af ... eplacement
this is somewhat extreme example.

I do understand how to reset the mcu. The probelm is I don't know how to generate a best new driving mode. Some peoples says after replacing the battery the car should be put to idle for 5min and slow driving for some, and then... I didn't remember exactly. My previous car 99 camry doesn't have this...

My car is 2006 XC90. I took my car to walmart last Saturday to replace the 7 years old battery. I oberserved the MPG calculated by the MCU gradually drops from 21.8 to 19.8 now in less than 50 miles. I read some articles saying it is caused by the learning mode. When the battery is removed, the MCU ...