I believe the 190e has an electric oil pressure gauge, therefore there is no oil line going into the interior of the car.

More likely it's either oil being sucked in by a leaky vacuum line, A/C oil from a leaky evaporator, or perhaps brake fluid from a leaky master cylinder.

As far as the odometer is concerned, it is mechanical, so anything is possible. They can break or wear out. I'd check the spedo cable first though.

__________________
2000 c280 Sport (looks like an upgrade, feels like a downgrade)
1991 190e 2.3 (sold)