When these cars were newer and more of them around I knew a few people who owned them. MY 94 SL2 coupe would get 33mpg on a road trip from my home in Phoenix AZ to L.A. Calif down I-10 if I used cruise control. If I drove it my self about 30 that was good enough for me and my favorite gas stop was just about 1 tank of gas away. A close friend had a later model sedan with a 4 speed and on the same trip he would average over 40 mpg.
The car would get good fuel economy in it's day. And still can if it is in good shape and reliable.
I think thought the 4 speed did in general get better gas mileage on a road trip.
I never checked it in town. It was and still is way too much fun to drive to get good fuel economy.

 

I've yet to do any highway trips with my '96 SL2 sedan. My work commute is 23 miles, round trip. Along with other local errands the first three tank fills have returned 31 to 32 MPG.

Since the late eighties I've kept a small note pad and pencil in each of my cars and written down the miles and gallons at each fill up and periodically done the math.

The most variable car has been my 1993 Mustang 5.0. 5 speed. When I bought it in '08 it averaged 22-23 MPG. Better on a longer commute. Some changes in the running gear, including gear ratio, speedo gears and intake manifold have reduced that to 20-21. The new transmission has a higher geared overdrive, and different speedo drive/driven gear combination. I'm curious what the new numbers will be. Better because of the higher overdrive or lower because I can't shift into OD as soon.

Your 30 to 33 mpg numbers seem quite good. In theory,, a manual transmission should get better mileage than an automatic, but I think driving habits can give the edge to the automatic for some drivers. Holding the speed at 65-70 with the cruise may net nearer 35. Fantastic numbers by the standards of a generation that grew up when 15 MPG was average.