Today only (8/29) you can head over here and use code TODAY20 to save an extra 20% off Groupons (there are a few exclusions). Groupons are a WAY better deal with a promo code!
You could click here to get 3 silver washes at Paradise Car Spa for $19.20 with code TODAY20, usually $47.97. The way it works is you hand in your Groupon the first time and you get two more passes for the future (I keep them in my glove box). Such a bargain! Enjoy!