[Andyman]

Your mpg is about the same as mine. I have a smaller engine but you have a manual transmission. I don't think your fuel economy is especially bad for short trips in cold weather.

Eliminating the warm up time would be helpful. If you accelerate gently during the first five minutes, you are not likely to hurt anything.

Probably the easiest modification to try is advancing the ignition timing a little. It's best if you have a timing light for this adjustment. Maybe you could borrow one from an auto parts store like Pep Boys or Autozone if you don't have one. It would be a good idea to check the repair manual for your car to understand the procedure. Mark the original distributor position with paint or a scratch before moving it. Keep it close to the recommended timing. I would avoid anything more than 4 degrees advanced from the standard setting. If it starts knocking, retard the timing a little (like 2 degrees) and test again. I'm not sure if your engine uses a distributor. If not, ignition timing adjustments may not be possible.

Check brake drag and wheel alignment since these can increase rolling resistance. Check if you can easily push your car on a level paved surface. If not, something may be wrong. If you lift wheels off the ground with a jack, you can check how easily they turn. Be sure to block wheels still on the ground with sticks, stones or other objects to avoid an accident.

One easy way to check wheel alignment is to drive forward, stop and measure how much a front tire sticks out horizontally past the rim, then drive backward, stop and measure again. If there is much difference (like over 1/8 inch) then an adjustment should reduce the drag. On cars that have independent rear suspension (like yours), it is useful to do the same measurement on the rear wheels too. Toe in causes the tire to move in (towards from the center of the car) when driving forward and toe out causes it to move out.

Avoiding snow tires will reduce rolling resistance. Remove them early when winter is over. If they are taller than the original tires, they might make your measured mileage less than your actual mileage. You might be getting better fuel economy than you think you are.

If you have a voltmeter you may be able to test all the electrical sensors that send information to the computer. Bad sensors usually increase fuel consumption.

Since your car is getting old, check all the vacuum hoses to see if any are hardened, cracked or collapsed.

Using a low viscosity synthetic engine oil and transmission oil should help reduce friction in cold weather.

Be sure to check the "65+ Efficiency Mods" at the top of the page.