This response from Pat Symonds at Renault F1:
Dave, I didn’t answer this initially as I didn’t know much detail about the answer!I had meant to ask someone at the race a bit more about them.
What I do know is that they are not capacitive discharge systems and everyone uses coils built into the spark plug caps now.
The ECU controls the low voltage power output to the coils and then normal inductance produces the high voltage.
If I can get some more info I will forward it.
Regards
Pat