On a trip through Costco, I was near the laundry stuff and a woman told me that she puts a tablespoonful or so of those scent pellets you toss in the washer in a snack or sandwich size ziploc bag then stab a few holes in it then throw it under your car seat. I did that maybe a couple months ago, and it still smells GREAT. Fwiw I use the Gain Strawberry scent, but any of 'em work.