I'm genuinely not a shill for Octopus but their EV tariffs do seem ahead of the curve as far as I can see:
-Lowest off-peak rate via Intelligent (7.5p, BG 9.4p, Ovo 10p)
-Longest off-peak hours (6 hours, BG 5 hours, Ovo - is anytime, but only for the car)
-Other leccy not premium rates for 'peak' times (29p, BG 37p, Ovo - to be fair seems their rates are same as price cap too, but not confirmed prices for July (2 days away!!)
These are rates for my area obviously, so may vary.
Everyone needs to do their own calculations but for me expect Octopus to be £300ish cheaper over the year (although that includes £50 bonus for being 'referred'). What I would say is check the standing and unit rates FOR YOUR AREA as they do vary a fair bit.