Here in Chicago, it's trial and error. Some of the cheap brands get good mileage and performance. Speedway mid-grade is what I use. I've been concerned with MPG and get 22 with the cheap stuff. Amoco and Shell get me 20 MPG on average, Mobile the car dosen't perform well and Citgo I only get 17 Mpg (its cheap) but with gas you don't always get what you pay for. I use mid grade and my buddy uses regular in his 85 190E 2.3 16 without problems. Give it a try, there are discussion in the forum regarding this.