CarTalk.com Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Power use and alternator output

Simple answer: Yes, you will get better gas mileage the less electricity you use. If you drive with your headlights on all the time, you will probably notice less than a 1/20th of a mile per gallon change. The amount of power being drawn just isn’t that significant compared to other factors like rolling resistance, wind resistance, frictional losses in the drivetrain, etc.