As above, does this mean the car is running too rich?, If so will changing the O2 sensor help? Car has 175k and is a 2000 TJ 3.5

Cold engine will smell on startup, incomplete combustion due to cold head and cylinder walls - that's why cold engines start rich on the mixture. Can't be avoided.
Noticeable even under an open carport, in a closed garage it would be very strong indeed.

Even a warm engine gets a shot of extra fuel on startup.

\Still worth checking for other causes though, like petrol stains near filler, tank, fuel filter, engine fuel rails etc.