Gas Mileage

[Tarfu43]

I've been driving a 2004 AWD Vibe for about a month now, and I keep track of all fill-ups. I calculated my gas mileage today and was stunned to discover that I was only getting 20-24 MPG! What gives? My commute is mostly highway miles and I'm not lead-foot. I do have slightly bigger-than-stock 215-55-R16 tires on it. Would that affect my mileage that much? Is there something wrong with my car? The book says my car is supposed to get 26-31 MPG. What kind of mileage are you guys seeing? Any comments would be most helpful.Thanks!

[northvibe]

You are driving in the winter, the gas quality is low so the co2 can rise. That affects mileage a lot. Also you drive a awd car. Your car is probably running just right. That sounds about right for the mileage at this time. In the summer you will see a jump. Have you made sure the car was tuned up? new plugs, oil change, fuel injector cleaner, tire pressure?

[prathman]

How long are your trips? The estimated mileage figures are for much warmer temperatures than you get in Minn. during the winter. The winter cold affects mileage in a number of ways: more time during warmup when the engine is less efficient, different gas formulation to make for easier starts but less efficiency, greater air resistance, usually shorter trips, tires and lubricants have more resistance, etc.

[ned23]

Quote, originally posted by Tarfu43 »I've been driving a 2004 AWD Vibe for about a month now, and I keep track of all fill-ups. I calculated my gas mileage today and was stunned to discover that I was only getting 20-24 MPG! What gives? My commute is mostly highway miles and I'm not lead-foot. The book says my car is supposed to get 26-31 MPG. What kind of mileage are you guys seeing? Any comments would be most helpful.First, how long is your commute? Highway mileage only applies when your car is warmed up. Most people, (including me) make the mistake of assuming their 25 minute commute is "Highway" when it's not. "Highway mileage" basically means your car is fully warmed up, you pulled off the highway to fill up, and you immediately got back onto the highway and drove non-stop with the cruise control on at 65 mph to the next gas station 250 miles later without stopping or cooling off the engine. It also means you minimized lane-changing and speed changing. I don't know about yoru commute but mine is anything but smooth on the hwy. Lots of lane/speed changing. Quote, originally posted by Tarfu43 » I do have slightly bigger-than-stock 215-55-R16 tires on it. Would that affect my mileage that much? Yes, it can. First, tire selection can affect your gas mileage by as much as 4 mpg (more if use put off-road tires). Second, the larger tires are going to make your speedometer register a slower speed and lower distance traveled then you actually went. Based on your tire sizes you could be running 4-7% off. So, your odometer may register 93 or 96 miles but maybe you actually went 100 miles. This will make your gas mileage appear lower. You can check your speed. Buy or borrow a good GPS unit like a Garmin Nuvi that has a screen that will show you your horizontal accuracy in meters and your speed. When you've got enough satellites for 10-20 meter accuracy, compare the speed on the GPS to your speedometer. At 10 meter accuracy the GPS speed should be accurate to within about 0.2 mph. Snow tires also cut several MPG off of your fuel efficiency. FYI, When I replaced my stock 2004 Tires with "Michelin Energy" tires, I got a boost of about 2 mpg.

[ou.grizzly]

May need a new CAT even though you are not throwing a CEL. How many miles on the Vibe?

[Tarfu43]

Everyone,Thanks for the comments, they are all valid. I'm not sure when the last tune-up was, but I bought the car from a dealer that has a good rep, so I assume they inspected the motor. I'll run it through the seasons, and see how the mileage varies. Thanks again!Grizzly - the car has 34,000 miles on it, and no CEL warnings.

[Tubaryan12]

Its winter.I normally get between 33-38 mpg in the summer months. The last month I have been getting between 28-30 mpg. Where you are is much colder than where I am so I wouldn't worry about it until May.

[Caretaker]

well I just got back from bear country in PA. I got 36 mpg highway going up taking my time in my 2009 1.8 automatic. After some NYC driving and trips up the mountainside, plus going 80+ mph on the highway coming back, I got a combined 31 mpg. It was obvious watching the gas dial that the Corolla engine does not like 80+ mph, nor my occational 90. Geez, and I traded in for the smaller engine so I would not drive as fast on the highway like my old 6 cylinder pushrod engine. Alas, there is always someone out there to take the ticket for me. It is good to be back without any stories of deer strikes, eagle attacks, or trees jumping out of the ground scratching up the paint.

[kunkstyle]

Quote, originally posted by Tarfu43 »but I bought the car from a dealer that has a good rep, so I assume they inspected the motor. Not an assumtion I'd make. My rule of thumb for buying used vehicles, no matter if it's dealer or private sale: oil change, spark plug change, and fuel injector cleaner, and at the very least inspect if not replace the air filter. Although assuming you're mpg is in us gallons, that's not bad for an AWD. The larger tires will affect it, as will winter fuels, as previously stated.

[keithvibe]

I have an 06 awd and that is normal during the winter months.I get 20-27mpg with mixed driving during the winterI get 26-36mpg with mixed driving during the summer.winter tires hurt mpg, winter gas hurts mpg, the longer warmups hurt mpg.

[NJVibe04Salsa]

Before your warranty runs out, get the transmission thoroughly checked to see if the viscous coupling slips. The AWD mileage has been a popular topic on the Vibe/Matrix boards. A number of people are reporting low 20's mpg while others are oddly up around 30. I have some suspicion that I may be on the verge of uncovering a big future-recall issue relating to the AWD component. Read my post over at the matrix forum:http://matrixowners.com/?showtopic=81422Have your Vibe checked out - and not just by the Pontiac techs because their standard diagnostic procedure fails to identify the problem if it exists.

[abyssvibeawd]

I have the same problem, AWD, not working, bad mileage, 20-23 in town, about 30 highway, winter time. I also get a whining noise from the rear at about 20 to 30 mph, sounds like the differential. I did purchase the car used just about 2 months ago. Bought an extended warranty from the Nissan dealer. Took it in, saying the AWD doesn't work, they did the same thing, put on rack, all 4 wheels spin, they said they called Pontiac and Toyota and they told Nissan that it is working fine if all 4 wheels are spinning. I asked them to stop the back tires, they said they could with the parking brake but that was normal. Well, I took it to Toyota dealer and they put it on the rack and determined the differential needs to be replaced, but the warranty I bought will only work at the dealer I bought the car from. So I took it back to them again, with the Toyota Diagnosis, they called and said the differential needs to be replaced. I am still not sure Toyota or Nissan know what they are doing, not sure the AWD will work after diff. replacement, which is scheduled next Wednesday. But it will only cost me $50 copay to get the differential replaced. Nissan said "it wasn't that noisy when you brought it in a week ago" I complained about the noise the day after we bought the car and the noise has remained the same. I know that the Viscous Coupling is connected directly to the rear Diff. I am not sure if the sound is coming from the Coupling or the Diff. I didn't get to listen to it when it was on the rack. The other thing I thought of is if you stop the rear wheels from spinning when on the rack and the drive shaft is still spinning going into the viscous coupling, wouldn't that be the best way of determining that the VC is bad? I will update after replacement of Diff.