Welcome Jennifer:
First, before the gas mileage tips, is some advice on the 2.3L Ford “Lima” engine. The oil level and condition is critical to the overhead camshaft lobe survival. Keep the oil clean and check it often. Otherwise this engine is a great little 4 banger.
OK…gas mileage. Is your car a stick or automatic? Due to the fact that these cars are much lighter than the donor cars their drivetrains came from, they will get decent mileage just on that fact.
Keep your tires inflated properly and the front end aligned…any drag kills mileage.
Keep the engine in tune and use synthetic lubes in the engine, trans and rear. Also in the power steering if your car has that option. In your colder climate this is a great thing even if you aren’t looking for better mileage. It’s expensive, but I use Royal Purple in all my vehicles. Their motor oil still has the scuff package that is missing from today’s SFI “SM” oils. Camshaft life is dependant on that zinc based scuff package.
Engine and mechanical mods like adding tube headers, low restriction exhaust system, CD ignition boxes, re-jetting the carb, distributor timing curve, hi-performance plug wires and such will also help a little with mileage, but help a lot in performance. Are they worth the costs??? In my opinion for gas mileage NO…performance YES.
These engines use a timing belt and if your’s is the original CHANGE IT. After all these years, it’s probably dry rotted. This is a critical thing and is well worth the cost to do it. It’s not a hard repair on these engines either. Change the tensioner when the belt it changed. You can get both cheap at http://www.rockauto.com . Use a 1975 Pinto as the vehicle application.
Forget the aerodynamics on these cars for gas mileage. How you use your feet on the gas and brake is the biggest gas mileage variant. No jack rabbit starts and no hard braking produce much better mileage. I started driving my ’89 GMC Suburban 5 miles per hour under the posted 65 mph speed limit on the expressways and Interstates here and my mileage improved significantly. I just can’t bring myself to go 55 though.