Originally Posted by Melanie B in NC
My husband insists he either read or was told that he should pull it (using our 2013 Highlander) in 3rd gear, not in Drive.
How does driving in 3rd affect gas mileage?
I cannot speak to the specifics of the Toyota Highlander.
My Honda Odyssey's 4speed transmission has "Drive", D3, D2, and D1.
"Drive" is the highest gear, and some call the highest gear "overdrive". This is where you find the best gas mileage. As needed, the transmission can automatically shift into any gear in sequence. But under some load conditions, like pulling a trailer uphill, the automatic shift will "hunt", meaning it will be in "Drive" and then downshift to "D3" then after a few moments it thinks it has enough momentum to go back to "Drive" and then after a few more moments it will think, oops now there's a strain that this gear is too high for, and go back to "D3". The automatic setting seems to be searching for a gear between "Drive" and "D3" and since that does not exist, it keeps ping-ponging between the two gears. To avoid this Hunting, the advice is to manually shift into "D3" which becomes the highest gear instead of "Drive". Now it will stop hunting. But the downside is that the engine will run at a higher RPM, which will decrease gas mileage.
I tend to tow in "Drive" on flat land (like the Central Valley) and in "D3" on hills (like the Grapevine).