As an experiment, I tried using the car exclusively in HV mode to see how far I could actually go on regular usage, since I always felt that the distance to empty range looks a little low. With a 11.4 gallon capacity and a 60 mpg economy, I should get about 684 miles. It's been 385.3 and the car is saying I have another 161 miles (137 miles short!)
it isn't calculated using the whole tank. there is a safety measure so dum dums won't run out of gas. it is usually a couple gallons, and should be specified in the owners manual
Gas light comes on with around 2 gallons left in the tank and the meter says about 30ish miles left of range. Its intentional so you don't run out of gas. 2 gallons could get you 120 more miles if the meter was accurate at 60mpg (it's not. Toyota overestimates mpg) but it could just as easily only be 80 miles if you're driving in really cold conditions on the highway getting close to 40MPG for that last 2 gallons.
As commented, DTE is based on the ~9.3 gal of gas. (11.3 gal full tank but the empty light coming on when 2 gal still in the tank). It is an estimation based on the previous driving record usually prior tank-full driving not the most recent driving on the current tank. Also, the mpg displayed on the dash is inflated. Toyota routinely reports anywhere from 5-10% more optimistic mpg than actual. You can use the DTE at fill-up to estimate your HV portion of mpg. DTE after fill-up above 500 miles is a good number, representing about ~53mpg. Read more on this thread: What is your DTE after fill-up?
60 mpg sounds a little optimistic. On a 2000 mile road trip averaging about 70 mph with no EV, I averaged about 45 mpg. Some of the long stretches were at 85 to 90 mph, though.
For me it’ll underestimate too since most of the time when the engine is on, it’s on for a short period. I rarely take entire trips in HV mode so my mpg on the HV side (if it’s tracked somehow) must be horrendous.
So I drove mine today until it said I could only go 1 more mile on gas. How much further could I have actually gone on that? My battery was full as well.
You have about 1.5-2 gals of gas and full charge. It depends on how you drive, but using an EPA estimate of 53mpg and 25miles EV range you can drive 100-125 miles further.