I switched to premium and am getting 32+ mpg highway....... (28 mpg combined according to the DIC) and have a lot more power. Part of that combined mileage includes a few controlled burnouts ...... LOL

 

I did another cross Florida state trip 449 miles and 13.7 gallons (32.7 mpg) when I refilled when I got home.. Average speed 55 mph. I used 91 octane as an experiment. Good mileage is all about driving technique. My last cross state trip I averaged about 35 mpg using 87 octane.

Both trips used non freeway highways with 55-65 mph max posted speed limits with several 45 mph sections.

 

I have an '09 with the stock 2.4 lt 17" factory wheels. I'm driving around 50 miles to work round trip and avg. Mpg. Is 27.6 50% hwy and 50% rural roads!

 

I'm doing about the same...50 miles round trip 45%hwy, 55% city and I'm getting about 27.4ish.

I will however say that my calculations and the puter are usually different. I use the miles/gallons and my figures are almost 1-2.5mpg HIGHER every time. I've tried premium and 87...with my commute it ends up being about even. Little better milage on Premium but cost offsets any real advantage. Can feel a slight difference in power though. Prolly just split the difference and go with 89

 

On my 07 with a auto 2.4 I am getting 30-32 on urban roads. mostly 55MPH speed limit except when you go through some of the small towns. Usually always use my cruise control other wise I look to see I am doing 70.

Bob

 

That's not city driving, at least not a congested city lol. My average speed is 19mph. I average 21.0mpg with 100% city miles over the last 1000 miles.

 

That's why I used the quotations. Denver "city" streets (anything non highway) are pretty wide open, 40-45mph limits most places.

 

I avg 29-30 all the time. I can get 32 avg, but crap is that a lot of work. Tire pressure is the key, run mine at 42 pounds rear and 43 front. Ride is a little stiff, but hypermiling is a challenge I enjoy. I can easily drop it down to 24 if I drive stupid. Use 87 octane gas, I actually see a drop in mpg if I use premium. Cannot run the AC and get these numbers, AC costs about 2 mpg in my HHR. My other car is an 07 Dodge Charger SuperBee SRT8 number 0991 of 1000, we don't discuss miles per gallon, only smiles per gallon.

 

I think your mileage will have a lot to do with the final drive gear ratio. Please see my new post in this section. God Bless, Marc

 

JEALOUS!! I miss my Charger!!

Premium actually helped me also. My right foot is the limiting factor LOL!