Before you measure any rest current your car has to get into "sleep mode". Keep in mind that in order for the car to sleep at all, it must be off and nothing can be "touched" (no opening of the trunk or doors, no pressing any buttons on the key fob, etc.) If something is touched, the timer starts all over again...
How long it takes for it "to go to sleep" I am not quite sure, but 60 minutes should be enough....=;o)....Rest current should be under 0,05 Amps (50ma)
For comparison my 1997 LS400 has a rest current of 24,8ma.