mpg drop

RedP5er

Member
My P5's gas mileage has dropped from ~30mpg to ~27mpg for the past 2000 miles. My driving habit and daily route remain unchanged (80% freeway, 60-75mph, occational traffic jam, etc.). Had 60,000 miles major tune up about 6000 miles ago (now at 66,000 miles). So, what could be the reason? New tires (205/45/16 Fuzion ZRi)? Winter gas? Any idea?
 
Winter gas. Is it idling rough at all? If so maybe dirty egr. Spark plugs/wires new or old?
 
i12drivemyMP5 said:
Winter gas. Is it idling rough at all? If so maybe dirty egr. Spark plugs/wires new or old?


Ditto. Did you get gas from a different place? How's your tire pressure? 6K, when was your last oil change?
 
i12drivemyMP5 said:
Winter gas. Is it idling rough at all? If so maybe dirty egr. Spark plugs/wires new or old?

The car runs smooth as usual. Feel pretty strong (probably due to the cool dry air). Spark plugs were replaced during the 60,000 service. Have been running Mobil 1 since 10,000 mile. Used to change oil every 5,000 mile. Now I change around 10,000 miles after switched to the new extended formula. Yeah, I know it is a bit long, but with 80-90% freeway each day, I figured it shouldn't be a problem. The new tires are actually a bit smaller than the original 195/50/16, but I really don't think it will lead to such a big drop in gas mileage. I suspect winter gas is the biggest culprit myself also.
 
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Pour some techron or fuel injection cleaner in your tank. Although, sounds like
the cause of the winter gas. Did you change or clean your air filter when you did the 60k service??
 
maitai92 said:
Pour some techron or fuel injection cleaner in your tank. Although, sounds like
the cause of the winter gas. Did you change or clean your air filter when you did the 60k service??

Haha, I was thinking about the same thing so I used the Chevron techron fuel injector cleaner in my last tank of gas. No change. Gas mileage still held at ~27mpg. They did change my air filter at the 60k service. The gas mileage had been normal after the service (I managed to get 440 miles out of a tank of gas, using about 13 gallons at one point) untill the last 2k miles. BTW, I am switching to K&N drop-in replacement soon. It is in the mail.

I am curious, when do they start serving winter gas at the pumps? When do they switch back to summer formula?
 
In California, I think they start switching to winter gas in November and switch back to summer formula in May. (I think) And that's when the gas prices goes back up again :(
 
I love people who worry about mpg. The prices are outrageous as it is, losing 3 mpg isn't really making that big of an impact on your wallet. I don't care how long it lasts, it's gonna run out eventually anyway! Life's too short to be worrying about how many miles you're getting out of a tank of gas!!!
 
snowblazin said:
I love people who worry about mpg. The prices are outrageous as it is, losing 3 mpg isn't really making that big of an impact on your wallet. I don't care how long it lasts, it's gonna run out eventually anyway! Life's too short to be worrying about how many miles you're getting out of a tank of gas!!!

Haha, I understand what you are saying. Although I commute about 80 miles per day, my P5's gas mileage is good enough for me not to worry too much about gas price. Paying $50-60 more per month is not enough to break my bank, fortunately. However, I pay much attention to the gas mileage because I see it as an indicator of engine heath. Trust me, I don't drive granny style :) .
 
RedP5er said:
Haha, I understand what you are saying. Although I commute about 80 miles per day, my P5's gas mileage is good enough for me not to worry too much about gas price. Paying $50-60 more per month is not enough to break my bank, fortunately. However, I pay much attention to the gas mileage because I see it as an indicator of engine heath. Trust me, I don't drive granny style :) .
Good deal. (thumb)
 
winter gas + winter air

off-topic: did your tires affect your ride quality much or do anything funky to your steering?
 
eting_pro5 said:
winter gas + winter air

off-topic: did your tires affect your ride quality much or do anything funky to your steering?

No, the Fuzion ZRi's have been great. It is excellent for their price. Perform very good in wet or dry. Less road noise than my previous Kumho Supra 712. The shop did a great balacing job. No vaibration on freeway. I think ZRi has one of the best combinations of price, performance, and comfort out there, IMO. Very satisfy with my choice (thumb).
 
snowblazin said:
I love people who worry about mpg

don't think people really care about the small price difference, but when there is a drop in MPG it could mean the car has a problem that has to get looked at/fixed!

i calculate it on a weekly basis and when it drops usually something needs a cleaning or changing......

-R
 
Protege52003 said:
don't think people really care about the small price difference, but when there is a drop in MPG it could mean the car has a problem that has to get looked at/fixed!

i calculate it on a weekly basis and when it drops usually something needs a cleaning or changing......

-R

You took the words right out of my month... (thumb)
 
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