Some comparative stats from www.fueleconomy.gov:
A 1984 Honda Accord (4 cyl, 1.8L, 4 speed auto) managed 24 mpg on the combined cycle.
A 2011 Honda Accord (4 cyl, 2.4L, 5 speed auto) managed 27 mpg on the combined cycle.
A 2011 Honda Civic (4 cyl, 1.8L, 5 speed auto) managed 29 mpg on the combined cycle.
The later Accord is larger, heavier, better equipped, cleaner, safer, but also returns better mpg.
The current Civic is perhaps the best comparison in terms of size and engine capacity to the 80s Accord, and does much better in mpg.