Gas mileage AC and the RX-8
 

Is it just me?
Little background, I drive hard, get about 17-19 MPG most of the time with about 50/50 driving. However, lately as summer is approaching, it's been 80+ degrees here, 92 yesterday. I use 93 octane, which is high test in Nashville, there is no 91. I've been running the air consistently.
What I've noticed, (which could be attributed to summer gas), that even running the a/c, driving hard, I'm getting about 21-22 mpg. I've never complained about the mileage, but was wondering, does summer gas make that much of a difference. Especially when the A/C is supposed to use about 20% more gas, (so I've read, can't confirm).

So, is it just me, or is everyone enjoying gains in mileage due to the switchover to summer gas.

BTW, I just read an article about gas prices, it said either Tokyo or Hong Kong it's about $5.35 US dollars a gallon, in Venezuala (sp) it's $.14 (fourteen cents) a gallon, due to their production.

I've been paying between $1.999 and $2.039 a gallon in Nashville.

Comments please....

Wow $1.99 for premium... haven't seen those prices for a while. You'd be hard pressed to find 91 for less than $2.35 here in Los Angeles.

All I can say is I've noticed absolutely no difference in mpg when running the A/C and when not running it. I also notice no real loss in power when the A/C is running. Maybe I'm just not perceptive enough, but every other car I've owned, I've noticed less power with the A/C on.

As for summer gas, it can make a difference, yes. That's a pretty big difference, though. Maybe your car is just getting broken in now?

Well, I bought my 8 in August of 03, have about 12,500 miles on it, I'd hope to say it was pretty broken in. However I remember last year it seemed about the same mileage, but that was in the break in and I didn't redline it or anything.
I've also noticed no noticable difference in performance with A/C on.

As far as gas prices go, the cost of living is more in L.A., in Nashville, I actually have a yard and stuff.
This is about 1/3 of my backyard in pic below

I can only speak for my car, but I have no difference in mileage using a/c, but that's probably due to the fact that the thing cycles every 5 seconds, and will be virtually useless in the hot weather. When the dealer figures out the a/c problem, and gets this system working right, I am sure I will notice a bit of difference in performance and gas mileage. I'm just waiting for them to either recall the a/c or figure out what's wrong so I can take it in for repair.

VikingDJ,

There's a TSB out with the A/C fix. I'm getting mine checked in a couple weeks. Click here:
http://www.finishlineperformance.com...07-002-04.html

I've read all the threads, and have not gotten any definitive answers. That's a bulletin and not a recall correct? I read many follow up posts on how that repair did little to nothing for helping a/c work better, and dealers are taking apart dashboards, trying to find other ways to repair it. From all the info I have read, this is still up in air, and there is no guaranteed fix thus far, and the a/c amplifier has not solved the issues for many people. PLEASE. Correct me if I am wrong, and there is in fact a 100% solution to this problem, and everyone's cars are getting fixed. If not, I'll just have to wait it out. Thanks!!

my A/C is cold

Re: Gas mileage AC and the RX-8
 

I never really thought about the winter/summer gas thing. Thanks for reminding us. I have noticed an improvement after getting the m flash and attributed it all to the flash, plus my spending more time in higher gears. Because the flash might have coincided with the summer gas changeover, I guess I won't know for sure until we go back to the winter gas later this year.

that's only 1/3 of your backyard?

well, depending where you live, it can be a lot or a little.

to me it's nothing.

and I think your mileage may just be lucky because getting better mileage with AC on is usually hard.

so far, i've noticed no difference in gas mileage AC on or off. I get 19mpg pretty much all the time and I just don't care.

Yep, no noticable difference in MPG or Performance while using A/C here, very nice.

I can get premium at some stations here in Houston for $1.87 but the highest I've seen is $1.99

The mpg on this car is oddly consistent. Nothing I did seemed to make a difference on the first 8 tanks. The only difference came with the last tank which was spent about 50% in stop and go freeway traffic and the other 50% doing about 95 mph. Got 3mpg better than all the other tanks. go figure.

BTW, the AC TSB applies to vehicles built through sept 03. Mine was built this year but as it's gotten warmer I have noticed it has the same cycling tendency. I'm going to wait for a more definitive fix before I even bother with it.

The A/C amplifier replacement absoultely fixes the cool/warm problem.

Additionally, I have a definate decrease in performance when my A/C is on.
Doesn't seem to affect mileage, however.

How significant is the warm/cool difference in the AC? I used mine for the first time yesterday and I could have sworn that I felt a temperature shift every few seconds...

Well.....I think more people are writing posts when they dont have the expected results from the AC amplifier fix than those who find it to be a godsend.

I for one have an odd observation that may or may not mean anything.

My car was a preorder. The very first group of US cars. I believe the build day is May 03. So every TSB or recall that comes down the pike always applies to my car. My vin ends in 0921.

One thing I never really noticed was the A/C cycling issue. I thought the system was not as cold as my last car....but not terrible like others have noticed. I had the earliest PCM version with all original hardware.

In early spring I get the "M" flash. We have a warmish stretch a few days later. On goes the A/C. The air gets nice and cold and then it felt like someone turned off the switch in the car.....less cool humid air blows me in the face. This goes on and on for awhile....getting less severe as 30 minutes or so passes.

I think....wow, this is what everyone was talking about, and it SUCKS. Not but 3 days passes and the A/C amplifier TSB comes out. My dealer gets it for me and installs it. I definately notice the difference. The cycling is far less severe. Not gone, but just about. In fact I never would notice the cycling in the current condition if I never had the previous problem. The air stays a more consistant temperature coming from the vents. It appears like it is working normal to me now.

So....the scenarios are as follows:

1. The "cool/warm" cycling was present from day one and I just didnt notice it for some reason.

2. There is a conflict between newer PCM versions(which I had flashed) and the old A/C amplifier causing improper A/C function.

3. The original A/C amplifiers actually can go bad. They may function normally for awhile (in my case six months) and suddenly stop working as designed. This would explain why since day one some owners had the problem and others didn't.

But it all boils down to the problem is been fixed in my eyes. The A/C does work(Now), and it cools to the point that I need to turn the fan speed to 1 or 2. Thats all I can ask for.

Give the A/C amp a chance if you are having problems. It worked for me.


side note---------

Speed Racer and i have the same situation. We were both preorders with same delivery time in the same state. Our VINs are only like 20 or 30 apart. Identical in terms of manufacturing.

He drove my car after the new amplifier was installed the other day and his comment was.... "My A/C has never been even half as cold as yours is right now."

I guess this is a pot luck thing, since several people have noticed no difference in cooling when having this done. Odds appear to be decent it will help, but I will not hold my breath on this one. It got 85 today, and I had it full blast. After about 20 minutes of driving, it did cool me off, but compared to my 95 vw golf, this a/c is very weak. It might just be weak to begin with, and I am expecting more. I would like it to at least have a more constant cold temp going through vents though, and since my car is in the vin range for the bulletin, I'll probably take it in soon, and have them replace the a/c amplifier. Either way, some a/c systems are simply better then others, and it appears the one on rx8 is mediocre at best, even when working right. Thanks!!