Yes.
I have read that the car body is advised but as it all works I've left it alone.
I do it as you do on a Mk2. I believe, IIRC, the CTEK has anti spark software.
However, the Safety Instructions do say:
"For batteries mounted inside a vehicle, connect the negative connection to the vehicle chassis remote from the fuel pipe".
With Stop/ Start, as stated in other posts , it must be connected to the chassis to bypass the charging sensor.
Can anyone point me to a good
assessible chassis earthing point on a Mk2???