The smell of anti-freeze inside is not a good sign. However, can you find any traces on the garage/driveway? I had a leaky heater core and the symptoms were coolant dripping alongside the transmission. This was traced to a drain from the heater core housing. There is a drain hole in the housing that leads to a rubber drain that empties along the transmission. (was that redundant?) Look also on your floor for coolant.

I think I noticed the smell only when the heat was on and in bad cases, you will notice that the heated air is moist and can condense on the windows.

__________________
Michael LaFleur

'05 E320 CDI - 86,000 miles
'86 300SDL - 360,000 miles
'85 300SD - 150,000 miles (sold)
'89 190D - 120,000 miles (sold)
'85 300SD - 317,000 miles (sold)
'98 ML320 - 270,000 miles (sold)
'75 300D - 170,000 miles (sold)
'83 Harley Davidson FLTC (Broken again) :-(
'61 Plymouth Valiant - 60k mikes
2004 Papillon (Oliver)
2005 Tzitzu (Griffon)
2009 Welsh Corgi (Buba)