My car smelled like syrup when the coolant was leaking from the head gasket. Maybe there is coolant being dumped somewhere?
That's probably it. I can recall smelling a maple syrup scent for a number of years at a certain isolated location just down the street from where I lived in a small city. Since there was a large General Foods factory about three miles away, I thought at first they were making maple syrup, but the scent was confined to just that one place. I now think it was antifreeze, which has a sweet, syrupy smell.