i recently went on a long trip and on a tank of gas in my 88 rx7 GXL i got about 350 km which is considerably better than the 170 km i got on a tank of gas that was all city, stop and go driving. What could be causing this problem and what should i get checked out? thanks for any help.

 

Stop and go driving will always use more gas; unless you have some crazy gearing. Look at some window stickers of brand new cars, the city and highway milage is usually like 10 mpg different.

 

i also had the same problem..i changed my spark plugs and that made a wolrd of differnce i got about 30 miles more to the tank that i usually got

 

I used to own an 86 GXL,typically on a long run in summer maybe 480-520 km per tank,around town in winter maybe 380-400 km.But the distance was somewhat variable depending mainly on the position of the right foot on that little pedal.