Here's a puzzler. I have a 2000 Beetle TDi. Until about 2 months ago, I averaged 40 mpg in the city. Two months ago, my mileage dropped progressively to 38 mpg, then 35 mpg. A month ago the battery died.
I put the new battery in, and for the first 2 tankfuls, I am back at between 40 and 41 mpg.
My driving pattern and habits haven't changed (95% city), nor have I changed the station where I fill diesel. I haven't done any oil changes, changed the tire pressure, or performed any other work on the car.
So why has my mileage returned to what it used to be after I changed the battery?
AC