EV charging rate (for all EVs and chargers) are set in Amps, and the rate of charging can only be adjusted in whole numbers (5A, 6A, 7A... 32A).
1A @ 230V = 0.23 kW. So if we see an excess of 0.4kW available, we’ll increase the charge rate by 1 A / 0.23 kW, leaving 0.17 kW of excess. If we see an excess of 0.2kW, we won’t change the rate of charge, and 0.2kW will continue to go to the grid.
It's not possible to track excess solar more accurately than this on any EV or EV charger.
