I can't remember ever getting anything as low as 18 MPG under ANY conditions.
My daily drive is 89 miles with about 20 miles of winding, narrow, paved farm to market road, 20 miles being freeway driving about 2 miles total through a small town with stop signs and traffic lights and the rest, wide two lane, hilly highway. I get from 25.5 to 27.5. I have very little boulevard stop light driving time to know, but I would be shocked if it fell below 20 under those conditions.
All these numbers are with ME driving. Remember that driving style is a HUGE factor in fuel mileage.
BTW. The manual transmission was also sent to the US in '88. There were about 700 '86's and about 300 '88's brought to the US.
Hope this helps,