Can I use all the gas in rex before your electric miles

[Ronmamaci3]

Am I able to use all my gas first on rex mode via hold charge. Can I empty the whole tank?

Will in transition to my EV Miles automatically without any issues?

 

[alohart]

A REx is propelled by energy from its battery pack regardless of whether the REx generator is running, so no transition in driving mode occurs when a REx engine runs out of fuel. The REx engine will just stop running so it will no longer be adding energy to the high-voltage system. The car will continue moving as it did when the REx engine was running until the charge level of the battery pack drops below ~3% at which point propulsive power will be reduced to enable the remaining energy to be used as efficiently as possible.

 

[Ronmamaci3]

Awesome explanation thank you.

 

[jadnashuanh]

You cannot engage the REx until the battery SOC is <=75%. This is to ensure that there is some 'space' to store the REx energy output. Once engaged, it tries to run at least long enough to warm up fully (about 10-minutes or so). After that, it will turn on/off and adjust RPM (and therefore output) based on how you are driving and the actual load on the car. If you manually turned it on, you can turn it off unless the SOC is at or lower than the automatic engagement value (you cannot adjust that). If there's no gasoline left, it will function essentially like the BEV does (minor possible exceptions). FWIW, the computer doesn't actually 'drain' the gas tank...there will be some unusable fuel left in it so that you don't damage the fuel pump, make it difficult to prime the lines, or overwhelm the filter.

 

[Tacfoto]

As far as can you empty the tank?, no. The USA 2014-16 i3s only let you burn 1.9 gallons of the 2.5 gallon tank. This could be software upgraded to use more, but how much more is a bit of a mystery. My 2017 USA model seems to be limited to 2.2 gallons.

In any case the REx seems to keep a little fuel in the tank. Probably to avoid harming the fuel pump.