hypermiler
He says he is motivated partly by his concern for the environment, but he mainly hypermiles to save money.
You can start hypermiling before you even get into your car by ensuring it is properly maintained and running as efficiently as it can.
I have hypermiled on occasion, although generally I consider it to be an extreme form of money saving.

SMART Vocabulary: related words and phrases

On the road: driving & operating road vehicles
aquaplaning
back someone up
biting point
boxed in
branch off
chauffeur
gun
handle
lock
pull
pull someone up
push start
range anxiety
reverse
road rage
run away with someone
skid
speeding
steer
ton

You can also find related words, phrases, and synonyms in the topics:

Environmental issues