my 83 with 2.6 I average about 19 combined. Its hard for me to get a good city vs highway rating. I live in the mountains of Santa Cruz and often have to punch it to keep up with traffic on the free way. When I drove to visit my Dad in Oregon last year I averaged 24-25ish on the highways. But they have been adding in more and more ethanol into the fuel in CA, which also kills millage since it dosent give as much power as real gas.

Also my engine is at 392,000 miles without a major overhaul. I've rebuilt the head but nothing on the bottom end. Previous owner of my truck tried "hot roding" the engine, so who knows what may be in the bottom end of the thing. Its all stock now, but I know my punching it up hills kills the millage.