Most people are shocked that I camp with the Toyota Prius on all night and the first question that’s asked is “how much gas does that use?”.
Update 1/3/2021: Initially the dashboard dial configuration for the Fuel Input was set to show two decimals, hence .02 was displayed. Once the selection was made for 1 decimal or no decimal the indicator read 0.
I remember owning a Chevy Tahoe and would never just sit in the SUV with the engine running, the thought of the motor just drinking the gas away at California prices is frightening.
Prius on the other hand, I can remember hearing someone mention how little gas was used when leaving the Toyota Prius in Ready mode and not driving. Makes sense why Taxi drivers in Prius’ never turn their car off…
Since I have an OBD2 Bluetooth device, I was able to use the included app on my tablet to view the gallons per hour fuel rate. For the record, we will call the “sleeping” state when the Prius is silent and “awake” when the Prius sounds like the engine is on.
As you can see from the above, an awake Prius uses roughly .69 gallons of fuel an hour.
Now when the Prius is asleep, it appears to only use .02 gallons of fuel an hour.
I typically do not use the A/C system to heat or cool the Prius while parked unless needed. Nights when it’s really cold, my heated throw comes in handy which is powered by my power inverter. When the A/C system is not used, power from the battery is only drawn from the power inverter and other electronics in the Prius like the radio. The Prius is in sleep mode more in this usage than when the A/C system is on, the Prius enters awake mode significantly more than when not using the A/C system.
It’s hard to get an exact number of gallons used when the car is just sitting in Ready mode. I’d like to believe if you average .69 and .02 gallons an hour over say 10 hours, .10 gallons an hour seems like a reasonable number to go with(I know the average is really .355 but I’m taking into account my car is in sleep mode more than it is in awake mode). That means the Prius would use one gallon of gas every 10 hours just sitting, we have to keep in mind that using the A/C system plays a huge role in how much gas is consumed an hour.