Even in fairly heavy (not yet Atlanta bad, but the infrastructure here is reaching bay-area/atlanta levels, soon to be Hell.A-Scape), an EFI 240, unless it's like -40 out, should get about 18ish city with typical driving habits.
So many variables for economy, but that's definitely below what the window sticker would suggest
. 20ish city traffic mix-27highway is a healthy/average N/A EFI 240 in a moderate climate.
Even if it's pretty cold out, no block heat, it should get warm within 2 miles, 240s heat up fast with the heater valve closed if the T-stat is any good, even non-turbo models without a watercooled turbo to exchange lots of BTUs right next to the hot exhaust into the cooling circuit.
My extensive 3 seconds of googling suggest that March in atlanta should be 43-66ish degrees out/mild/moderate?
Even navigating stressful San Francisco hills/horrible traffic on terrible california gas with stuff on the roof, the beater '87 245 would get ~18-19ish. Coolant Warm-up should take 5?ish minutes of driving or ~1 mile cruising at 60mph steady in the flat with the heater valve closed on a 45(ish)? degree day?