What was the midsize car to beat in 1983? According to this slightly delusional vintage Chevy commercial it was clearly the Celebrity. No import at any price could match "the room it gives you for the mileage it gives you at any price".
According to this commercial the Celebrity was capable of an EPA estimated 24 mpg around town and a non EPA estimated 39 mpg on the highway. We presume this lofty mileage aspiration was assuming the Celebrity buyer opted for the 2.5 liter Iron Duke Inline 4 and only drove on downhill highways going 46 miles an hour.
As someone who grew up in a seemingly invincible Celebrity wagon (Mom still has it in the garage—212k on the original 2.8L engine/transmission) I hold a certain sentimental affinity for these mediocre midsizes. Even so, I feel safe saying with a realistic set of mileage estimations plenty of imports wouldn't have had an issue matching the Celebrity.