Do reusable bags mean worse mpg?

I am wondering if the new push toward green bags will help the environment. I’m thinking most people will carry the bags around in the trunks of their cars, ready to use when they go to the grocery.

Trouble is, any weight you add to your car burns gasoline, even a very small weight; so the weight of these bags constantly in the trunk is going to cause more gasoline to be burned. Thus I don’t know if the total environmental toll is less than from plastic bags, which people didn’t carry in their trunk. Does anyone out there know?

Greg Dahlen
Glendale