Went to Knoxville from Elizabethton Tn., yesterday. We drove a total of 308 miles. 200 miles, there and back were highway driving, the rest was in Knoxville city. Refilled tank again today with 10.2 gallons of regular unleaded in our 94 Olds Cutlass Ciera 3.1L v6 with 100K+ miles on odometer. Before we left, I filled up and poured 1/2 oz EcoTek-1 in tank(1 oz treats 20 gal. so, 1/2 oz for 10 gal). So, according to the calcuclator, that's comes out to 30 MPG. According to the sticker on this car, new, it should get 26 MPG highway/17MPG city. Combined city/hwy, we got 30MPG using EcoTek-1. Not bad. Not bad at all.