The cash was unearthed by the Vidhana Soudha security officials during a routine security check this afternoon, a Cubbon Park police station official said.
The owner of the car, Siddharth, was being questioned, the official said.
"Right now we are not in a position to say anything on this count. We have brought Siddharth to the Cubbon Park police station and we are interrogating him," the official added.
To a question whether the unaccountable money was meant to be handed over to a minister as was being speculated, the police official said, "We are also looking into it... The interrogation is on.