According to fueleconomy.gov, my car should get around 24 MPG, so I am getting a little less than that. But it is definitely slow.
I have had a mechanic check the car out. Compression was good, and the car seemed to be in good shape. I think that the speed is not due to a problem with the car, but is just not created as a quick car, but I could be wrong. The car is a 3 speed auto, and it is rated at 84 horsepower.
I had a 1989 Aries with the same engine/transmission combination. Super reliable car, always started. I did get much better mileage than you describe though (about 22mpg city and 30-32mpg highway). As with any car, frequent heavy acceleration and under-inflated tires will take their toll on fuel economy. I got the car when I was 17 and stood on the gas quite a lot and it cost me at the pump. With the automatic, these cars are indeed quite sluggish due to the way they are geared. The manual cars, like the other respondent's Omni were noticeably quicker and even better on gas; the Omni and Horizon in particular because they were the lightest cars equipped with these engines. Also, the actual power rating for a 1989 2.2 with fuel-injection and Federal or Canadian emissions is 93hp.
As far as reliability goes it has been a wonderful car though. It has always started, and is excellent in any kind of weather (hot or cold. Besides a few mechanical problems as long as you keep up the matainence, It will last a long time. I have been happy with it as a around the town car, but am unable to travel the freeway, I can get it up to about 60mph tops on the freeway. So I am looking for a car that I can travel freeway in, (right now I drive on regular streets to get everywhere). All in all has been a descent very reliable car.
Have had my '89 Shadow since 1989. Gas mileage isn't great now, but for the past ten years, it was my secondary car so I hadn't been too concerned. Due to a recent accident, my '89 Shadow is again my only car. It'll get me to where I'm going 'til I decide on a new car. In spite of a few issues here and there over the years, it has lasted as long or even longer than many foreign cars. People laughed that I was keeping the car and told to get rid of it years ago, but it's almost the end of 2012 and my '89 Shadow is still running.
I am a big fan of Chrysler products from the 80's. I owned a 1988 Daytona with the Mitsubishi 2.5 engine. It was a very good car, and was traded at 100,000 miles.
I also owned a 1990 Dodge Omni with the awesome American-made 2.2 non-turbo 4. It was an incredible car that would literally leave my RX-7 in the dust. It was rock-solid reliable, and was sold with just under a quarter million miles. Total repairs included two timing belts, two brake jobs and one heater hose. The A/C worked perfectly when I sold it, and it had never even required freon.