2004 Gas Mileage

I bought a new Sienna CE on February 27, 2004. I drove home from the dealer, 70 miles, filled the tank brim full and drove 597.5 road miles before a complete fill up of 20.4 gallons, which equates to 29.289 mpg. I was ecstatic that a brand new vehicle could get that kind of gas mileage, especially considering that first tank of gas was from a Dallas area station which is in an EPA non attainment area which means the gas has additional additives which usually lower gas mileage. HOWEVER, since that time, my road mileage has run from around 21.8 to a best of 27.04. These two extreme readings occurred in December 2004 and January 2005 on the same stretch of I-20 east of Dallas, not using the air conditioner and under similar driving conditions and weather. The original sticker on the window stated that road mileage for a V6, 3.3 L engine should run 16-22 mpg in the city and 22-32 mpg on the highway, with average readings 19 mpg city and 27 mpg highway. My city driving which is mostly freeway has never been better than 21 mpg and is usually 18-19 mpg. This is my road vehicle and is rarely used in town. Previously, I owned 4 Camrys, 1995, 1996, 1998, and 2004 models, and consistently got better road gas mileage than the EPA ratings. I am very disappointed with the Sienna's performance and the engine seems undersized. It downshifts from overdrive on most small hills and has to wind up just to get on a freeway. By comparison, I have a 1998 Windstar which I drive the heck out of, no babying along like I do the Sienna. The Windstar has over 187, 400 miles on it, has a 3.8L V6 and is very strong. I drive it back and forth to Dallas and usually get 22-24 mpg, compared to 18-19 mpg on the Sienna on the same stretch of interstate I-35E. The dealer has had the Sienna twice and says everything is within spec. I noticed on the 2005 models with the same engine that Toyota has lowered the mileage estimates to 19-26.
ANYONE have any comments or suggestions?

I also have a 2004 Sienna, it is an LE and the first tank of gas we were getting around 28-30 mpg and now 17 to 21. 90% of our driving is freeway and have had the Sienna into the dealer 3 times for this and no one can come up with an answer. I used to be a Toyota mechanic but that was more than 10 years ago. A friend of mine who is still at a toyota dealer( 25 years experience) told me to not drive in overdrive(5th gear) because it bogs down the engine unless you are consistently driving more than 75mph for a long stretch, and that I should leave it in 4th gear to see if that makes it better since speed limits in my area are 55 and 65 mph. We are trying it right now to see what the mpg is. When i have results I will post them.

We have an AWD and the on board computer says 19.4mi/gallon for mostly freeway driving (90%+.) As I read somewhere EPA results are rarely acheived, as well as from experience, as they have some sort of weird test method. It is interesting to note that you say your other cars have actually acheived greater than the EPA rating. You also stated something else that may be part of the reason, I noticed that EPA rates for the 3.3L engine, and this is shared with other Toyotas, (I think a Camry.) The Camry (3.0L) also shared it's engine with the Sienna and Solara. Could it be the EPA uses an average, which of course would disadvantage the larger and heavier Sienna?

Consumer Reports got 30 mpg in highway driving with 2004 Sienna 2wd with no complaints about power. Let the tranny stay in 5th gear for best gas mileage. 3.8l Ford engine will have more low speed torque for better feeling of power.

The way I understand EPA ratings, they are supposed to reflect a specific engine in a specific model of vehicle. The car makers and dealers try to explain away the EPA ratings if their vehicles don't meet or exceed them. The fine print on the window stickers is what a buyer should use as their standard, not all the dealer BS. So far as I'm concerned, the Sienna has a problem with acceleration from a stop, lack of power in hilly terrain and in gas mileage performance.
=============================

We have an AWD and the on board computer says 19.4mi/gallon for mostly freeway driving (90%+.) As I read somewhere EPA results are rarely acheived, as well as from experience, as they have some sort of weird test method. It is interesting to note that you say your other cars have actually acheived greater than the EPA rating. You also stated something else that may be part of the reason, I noticed that EPA rates for the 3.3L engine, and this is shared with other Toyotas, (I think a Camry.) The Camry (3.0L) also shared it's engine with the Sienna and Solara. Could it be the EPA uses an average, which of course would disadvantage the larger and heavier Sienna?

well i did the driving in 4th gear thing for a tank and my gas mileage did not increase or decrease at all it stayed at about 19mpg.

I have a 2004 Sienna CE also. I get 21 - 22 MPG hwy with AC on and at 70 - 75 MPH. In town the milage is much less, I want to say about 15 MPG. It is at the very low end of the EPA MPG rating.

We have an '04 which we use to pull a horse trailer. Power is not a problem, although it downshifts a lot, sometimes two or three gears on a moderate hill. As long as the engine is reving 4000 RPM or so it has lots of power. We have been amazed at how good our fuel economy is. The Seinna does better (9.5 L/Km overall) than our '01 Maxima or our '06 X-Trail. On long trips we take the Sienna to save fuel!

Have the 04 LE 8 seater and most used for short trips around a small town during the week and longer 40 miles or so each way on the weekends. On board computer avg is 22.1 mpg. I can't complain as my wifes 02 altima gets 24 for about the same use and my 03 S10 crew 4X4 gets only 14 at best (all in town though).

I leased a 2005 LE 2WD 3 years ago and now have 36,000 miles on it. Always used Mobil 1 synthetic and ran tires at 30-31 lbs pressure. Just last month took a trip with 3 people and suitcases, and still was getting 29.5 on moderately hilly interstate driving 65 on cruise with AC.

Now, last week, I just bought another 2005 LE 2WD to replace my leased one (because residual is too high to purchase) and I bought this one for $3000 less than what the residual is on the leased one. However, mileage is a disappointment. Installed new air filter and changed oil to Mobil 1 just like the other one. Only difference is that tires are 28.5 lbs.

I'm getting 24.5 on the highway driving 65 on cruise, and barely able to hold 17mpg in town. I consistently was able to average 19.5 on my leased one in everyday city driving. I know the 2lbs of tire pressure will make a little percentage difference (Obama are you listening?), but not account for this big of a difference. Oh, and the 24.5 highway on the new one is with the van empty and just me driving.

A bad O2 sensor will light up the check engine light, so the problem can't be one of those. The one I bought has $51,000 miles. It does have cheapo GT Radial made in Indonesia tires on it and I don't know what their rolling resistance characteristics are.

I'm thinking now of selling the one I bought for a profit, and using the money to buy my leased one before turning it in. Only difference is, the one I bought has 4 more years of a Toyota Certified Platinum bumper to bumper warranty and my leased one will not have anything but the 5/60,000 powertrain warranty. But, my leased one hasn't been in the shop at all in the 3 years I've had it.