I'm the original owner of 2003 G35 coupe, 6MT. A few weeks ago, I noticed a coolant smell when getting out of the car after driving for a while. I noticed coolant on the bottom of the splash guard by the reservoir side of the car. My reservoir was near empty. I filled the reservoir to the max full level and didn't notice any leaks. Does anyone have the same issue with the coolant leaking? The car has not overheated. I've changed the thermostat a few years back and six month's ago, had someone change coolant. Anyone experiencing the same problem?

 

You can easily take the coolant reservoir off and check it for cracks, before you do that check all your hoses including the one from your radiator cap to the overflow. If you can't find where the leak is have your system pressure checked, it will show up.
Gary