Steve,

From one old Cajun to another, thanks for putting some numbers to the equation. Your figures give me the incentive to do a test of my own. If my results are the same as yours, there would be value in switching to Premium.

Mike,you should go at least two fillups with premium for a better test.

Thanks, Joe. I'll remember that when I do my test.

My test was over 3 round trips and I did notice that over a single tankful, the results were not consistent. There are variables that we probably don't notice that impact the results. That is why more samples result in better data.

My trip computer seems to be a little optimistic on mpg, but it is not far off. Normally it seems to be around 1 mpg higher than checking mileage and fuel added.

For a car this comfortable and this fast, I think the mileage is fantastic!
Steve

I've played with 87/91 and while 91 is definitely better, I noticed the biggest difference when I changed from regular oil to Pennzoil Platinum synthetic. Night and day difference in smoothness and engine response. Less grumble, and more willing to leap to life.

On my return trip from Houston, my fuel mileage dropped to an avg. of 32.1 mpg. That's still great, but about 2.5 mpg less than on my way there. I believe I can point to 2 reasons why my mileage was worse:

1. I could only find fuel with 10% ethanol in Houston.
2. I kept up with the traffic that averaged about 75 mph.

Now that I have about 1000 miles on my ES, it feels like a comfortable old shoe (a good thing). Each time I drive it, I know I made the right choice.

That 32.1 mpg is about what I get on my '07 if I keep the speed under 70-75 on flat terrain. If it's real windy (which isn't uncommon around here) or hilly it drops to 28-30 depending on conditions and speed.

Ditto! We drive to Pitt once a year and I usually see 32 to 33. Last year I drove into a stiff head wind and it dropped to 30. Looking forward to this year. I got the tranny flash done and it resolved my flaring. Better late than never right?

Anyway, I noticed my fuel ecomony improved. I picked up 2 mpg around town. Getting right at 26 now. Nice!