Mileage on 2003 Highlander

I've only had the 2003 Highlander for a month or so. Mileage has been all over the place. The worst has been 16 while pulling a small trailer. My best was 24 until yesterday's trip which was 30. I have checked and rechecked my figures and calculations.

30 seems quite high. Yesterday's weather was rain. Roads were state highways and a few small towns. I kept within 55 mph except for towns. Did not use A/C. Windows were up. Did use circulating fan.

A few weeks ago I switched to Redline synthetic oil.

Is it possible the digital odometer is off? I love the higher mileage, but I am suspicious.

Reply to
franz fripplfrappl
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I would think it is more likely that you didn't fill up the tank completely when you measured the amount of fuel used.

Jeff

Reply to
Jeff

I thought of this, too. When the gas pump shuts off at the nozzle, I try to pump in a few extra squirts.

Any idea how much space is left in the tank when the nozzle shuts off? Would this vary among filling stations?

Reply to
franz fripplfrappl

It is possible that the odometer is off, but not inconsistently. In other words, if it is off by .1 miles per mile at 55 MPH, it will always be off by that amount, not more on some days and less on others.

A lot of things affect fuel economy. Obviously, pulling a trailer adds weight and drag, which have an adverse effect of fuel economy. Having something on the roof rack also adds weight and drag.

Stopping, idling, and accelerating have an adverse effect, which is why cars generally get worse fuel economy in the city than on the highway. Driving at a steady speed means that the transmission is in overdrive with the torque converter locked so fuel economy is improved.

Using the AC has a slight but probably not measurable adverse effect on fuel economy, perhaps 1 MPG if it is not used for an entire tank of fuel.

Driving with the windows up usually reduces drag, which has a positive effect.

Cool, moist air is denser than hot, dry air so it mixes with fuel more completely.

Engines operate more efficiently when completely warmed up, so if the trip is long and the engine stays warmed up, you will get better fuel economy than the same distance made up of many short trips where the engine has to warm up each time.

Fuel pumps click off at different times, so there is a pretty big variance between pumps. By the way, trying to top off the fuel tank until the fuel is at the top of the fuel filler neck is not good for the evaporative emissions control system and can contaminate the charcoal canister. When the fuel pump clicks off, you can round up to the nearest quarter or maybe dollar, but topping off after that is not a good idea.

Reply to
Ray O

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