[gyozadude]

Based on odometer readings alone and amount of fuel pumped over the last 3 fill-ups, our Sienna 2001 XLE gets about 22.2 mpg and the Sienna 2002 Symphony gets around 23.6 mpg combined city and hwy, although probably distance wise, most of it is hwy, but time wise, about 50-50 city-hwy. To calibrate the hwy mileage on our last road trip, we drove up from near San Jose, CA to Richmond, British Columbia. That was 1015 miles according to the odometer, and the GPS said it was 1009 miles. Not too bad in terms of error. If I trust the GPS unit more, and averaging 36.25 gallons total for one way, that's 27.8 mpg hwy for the Sienna 2002. That's not shabby considering the section of snow we had to get through from Salem to Portland, and speeding along at 70+ mph.

I recall getting 28.5+ mpg on a summer trip once with A/C on most of the time, but we took our time and averaged only 62 mph at just a little above 2000 rpm. There appears to be a sweet spot for mileage, RPM and relative wind speed.

But I do some basic things to make sure I maintain good mileage:

a) change 5W30 motor oil and automatic transmission fluid regularly
b) change air filter regularly and clean out throttle body of gunk buildup
c) check and change spark plugs and ignition wires regularly
d) keep tires inflated to proper tire recommended pressure
e) use detergent gasoline and add FI cleaner additive regularly
f) drive usually with over-drive on and maintain engine RPM at about 2200 rpm
g) engage cruise control frequently - it's more steady than my foot
h) drive on the right and leave lots of distance so I rarely need to use my brakes.

I'm sure other folks' mileage will vary!