You smell antifreeze inside the car when you first start the car and disappear when you drive a few meters away of the 2007 Toyota Matrix. You do not find a leak on the ground.?

You may have a leak in the radiator or radiator hoses, but first check to see if the drain plug under the radiator is tight. have you checked your coolant lines to and from engine and rad?

Good place to start, however... Most vehicles emit more coolant as they cool.Most conjoined parts made of dissimilar materials cool/contract at different rates, therefore becoming leak prone. Sometimesthey may not leak until the car is almost completely cool and then seal back up when it begins to warm after running for a few minutes. Sometimes what happens is you will get a collection of coolant(aka antifreeze)in an area overnight and when the vehicle is started and begins to warm, the coolant stops leaking, what is there burns off (hence the smell) and then the whole cycle begins itself when the vehicle is parked again. If you provide the vehicle make/model I may be able to pinpoint it a little better for you.