Here is the EV recharging policy shown on Dollar's website:
https://www.dollar.com/AboutUs/GeneralPolicies.aspx#EV
CHARGE PURCHASE OPTION (CPO)/EV BATTERY RECHARGE FEE/UNDERCHARGE BATTERY FEE – With the purchase of the optional Charge Purchase Option (CPO) for a fee of $35.00 at the time of rental, You can return the EV at any charge level above 10%. If You return the EV at the same charge level as at the time of rent, the CPO charge will be removed. If You do not elect to purchase the optional CPO and You return the EV with a charge level less than 70% You will be assessed an EV Battery Recharge fee of $35.00 unless the charge level at time of rental was less than 75%. If the EV is rented at with a charge level of less than 75% no EV Battery Recharge fee will apply at return. If You return the EV with a charge level less than 10% an Undercharge Battery fee of $25.00 will apply in addition to any applicable EV Battery Recharge fee.
The way this paragraph is worded, the customer would be better off not purchasing the CPO. If he purchases the CPO, he needs to return the car "at the same charge level as at the time of rent" in order to get the CPO charge removed and save $35. However, if he doesn't purchase the CPO, he just needs to bring the car back with a charge level of 70% or higher in order to avoid the $35 charge. Furthermore, "if the EV is rented at with a charge level of less than 75% no EV Battery Recharge fee will apply at return." The sentence should either say "rented at a charge level of" or "rented with a charge level of", but not "rented at with a charge level of."
Let's say the initial charge level is 80%. If the customer purchases the CPO, he needs to bring the car back at 80% or higher to avoid a $35 fee, but if he doesn't purchase the CPO, he needs to bring the car back at 70% or higher to avoid the $35 fee.
If the actual policy at Dollar is that the customer needs to bring car back with a charge level within 5% of the level when it was rented in order to avoid the $35 fee, it should say that on the Dollar website. I think a better policy would be to charge the customer $1 for each 1% decrease in battery level upon return and to offer a $1 discount for each 1% increase in battery level.