A mechanic told you if you disconnected the negative battery terminal for 15-30 minutes the BCM would re-set itself and your mileage should improve you have an 2003 Chrys T and C Would this cause any?

A mechanic told you if you disconnected the negative battery terminal for 15-30 minutes the BCM would re-set itself and your mileage should improve you have an 2003 Chrys T and C Would this cause any?
well by doing this this will only stall the computeruntil the computer resets itself then it will remember its last setting and return to its normal. To improve millage you need to change items such as fuel filter, tune up make sure tires have the right amount of psi and injector cleaning. This should improve gas mileage