My 1993 Ford Escort Wagon (yes, I still own it) has absolutely no trouble passing State of Washington emissions laws. It's not even close to the limits.
My vehicle currently gets roughly 35 mpg highway and 30 mpg city. I know it's simplistic to use gas mileage as a proxy for gasoline conversion efficiency, but - it is not obvious to me that there's been significant improvement in gas engines over the past 20 or 30 years. I don't see a lot of similarly-sized new cars that do better than - or even as good as - my old beater.
I drove a 1993 Mercury Tracer wagon similar to your Escort for 18-1/2 years. It was a very reliable and durable car. I sold it to the brother of a co-worker 3-1/2 years ago and still see it every now and then. I got 30 to 31 MPG on my daily commute.
I replaced it with a 2012 Ford Focus. On the same commute route, I have averaged 36 MPG on the 46K miles it has on it now. The Focus has almost twice the horsepower of the Tracer. (160 vs 88). Yes there are similarly sized cars that get worse milage than your Escort, but technology has improved efficiency.