The disadvantage I found with using the car's timer is that I could not have both pre-climate at an exact time and have charging finish within two hours of departure.
I got around that by using the timer in the EV-SE instead. OpenEVSE Advanced 48A
is $600 these days, 4-week lead time for the assembled version.
Though I own three of these, I don't know that I recommend this unit anymore, they still don't have the ability to perform firmware updates to the controller via OTA, only by disassembling -- removing the front cover -- and using a separate AVRISP programming tool, which is pretty techy for a consumer device (the Wi-Fi module, ESP32, does
allow OTA firmware updates since v3, but still no controller firmware updates). But you do have firmware updates available, which I consider better than "you bought it, there it is, live with it". And, still no https
On my oldest unit, I've updated the controller's firmware twice since I bought it in 2017. I took good notes, it helps, unless you program Atmel microprocessors routinely; sadly, I do not.