The FARTHER that I drive along this road, the FURTHER my bad memories get.
Did you notice the difference?
Well, I think you got it:
FARTHER should be used when you talk about physical distance or position.
while
FURTHER should be used when you talk about degree or time.
Take a look at some other examples:
Your house is farther than I thought.
We hope that the gas prices drop further so we can afford this trip.
Comment about any further information you have.
see you later :)