35 mpg at 65 mph !!! the 31.69 was without even trying , average from a 370 mile trip. i tryed using the 93 octane before. i got a small gain , but not enough to justify the cost. i got 08 2.4 auto. i thought i'd try again since gas price dropped slightly and i got a discount from Sheets gas station. also since i took off the oem cold air "wooly worm" tube , added the dynomax straight thru muffler, and added the 0-20w oil....30.5 mpg at 75 mph. i will continue to test it a little more. i think it may be worth the extra cost of the 93 octane now since it seems as the combination of the mods and the 93 oct have given better results than just the 93oct before the mods. it may still not be cost effective. but it is amazing me.

 

I recognized a little better mileage than that AND I didn't have any engine mods. It was on a 8000 mile trip. There's a thread about it, if you're interested. My findings, after driving the exact same route in each direction (for those that need help....4000 each way) AND using the same driving principals, was the price of premium fuel is a break even on mileage......about 8%, if I remember correctly. I do continue to use premium, however. I, in everyday use, put very little mileage on my cars. About 3000-4000 per year, not counting LONG trips. The difference in price, is minimal at this point.....about $20 per year.

YRMBD

 

What did you replace the intake tube with? I've been looking to get rid of the OEM piece o crap.

 

thats great........i was only getting 27mpg on a good day before i made any mods. and i was trying my best to improve , cuz of my 275mile a day route, 6 days a week........i've seen others get better and worse mpg than i do. there are lots and many variables for what makes the mpg. i think most idifferences are due to drivers style, speed, and psi in tires. what is $20/yr to you would mean $40/month for me , at 85,800 miles/year. or more. i'm getting 93 oct for 2.11 9/10 now. reg is 1.91. even if i get it down to 8 gal/day , thats , $41.60 dif in price/month. anyone know where i can get a hyrogen fueled car?

 

My experience has been about the same as Snoopy's. I get 31 on the freeway using 93 without even trying hard. No mods, and we have to use E-10 here. When I tried 87 octane, I got about 29. As has been said, the cost savings is pretty much a wash. When it was $4.15 a gallon, I did the math and found I was saving about $100 a year by using 93. Now its probably closer to $25 a year. I keep using 93 because it runs a bit smoother and there is a notable power difference at freeway speeds.

 

i haven't put anything in it's place yet. some say and or think that it is not good because they think or say that it is sucking hot air. i think that the only time it will be sucking hot air is when it is sitting still. also if you look at some of the $250+ cais you will notice that they do not go thru the firewall or fenderwell cold air hole. if you sit a round filter in front of that hole as most of the aftermarket cais do , it is still sucking "hot" air from the engine bay.....i would think that even a radiator hose would be better than the wooly worm , if you could find one that size. the oem wooly hose i took off mine was partially collapsed , more oval than round.... if i can find the time and energy i would like to make a intake from spectre brand cai parts from the napa store.they have a universal maf piece. the napa guy said it is for imports , but i think it can be made to work. also to fabricate a box for the filter to sit in. simular to k&n , gm performace , and others. but instead of it sitting on top of the engine , have it sitting next to the fenderwell cold air hole and sealed to the fenderwell , not just sitting in front of it.....anyhoo , it seems to be working good as is , just by simply removing the wooly worm.

 

Just FYI, I found a Supplement page in my owners manual that reads:

"If the vehicle has the 2.4L L4 engine (VIN Code V) or the 2.0L L4 engine (VIN Code X), use premium unleaded gasoline with a posted octane of 91 or higher. You can also use regular unleaded gasoline rated at 87 octane or higher, but the vehicle's acceleration could be slightly reduced, and you might notice a slight audible knocking noise commonly referred to as spark knock."

Sounds to me like a minimum of "mid range" octane fuel would be recommended and for as little as I drive mine, I'll be filling up with premium from now on.

 

I don't care if people don't believe me, but I SWEAR that I drove from Frankenmuth to Petoskey (about a 200 mile drive) going 60 on the expressway, and I got slightly over 40 mpg in my Lumina. I added the numbers multiple times, and it still came out to that.

Say what you want, but I still know that you get better MPG with 93 octane. Now that it's summer and I have the truck out, I'll probably start putting it in the HHR. (Only because I fill up with the truck and get gas cans, and I run premium in the truck)

 

I have an '06 1LT automatic, and get 25 mpg around town and 29 hwy on 87 octaine. No mods on the car. Seems like I read somewhere that higher octaine would not be good for my type of HHR, however if premium gas would be beneficial on the hwy for long trips, I certainly would want to try it. Any suggestions?

 

A 1LT can be either a 2.2 or a 2.4. I have a 2.4 1 LT and it is recomended to run on 91 octane. 2.2's should run well on 87 octane.

So do you have a 2.2 or a 2.4?