What is mpg for a 1984 Chevy G20 van with 350 engine automatic?

The MPG for a 1984 Chevy G20 van with a 350 engine and automatic transmission is notoriously low and highly variable depending on several factors: driving style, vehicle condition, load weight, terrain, and even tire pressure.

You're unlikely to find a single definitive answer. Expect figures in the range of 8-12 MPG in mixed city/highway driving. Highway driving might push it slightly higher, but city driving will likely be significantly lower. Anything above 12 MPG would be considered quite good for a vehicle of that size and age.

Keep in mind this is just an estimate. Actual mileage will vary.