Cars are often people's third-most expensive investment, coming in just behind homes and diamond-encrusted scale models of homes. Look out for number three with today's Groupon: for $49, you get a mini detail for a car at Planet Auto Wash in Manassas (a $115 value). There is an additional $10 fee for vans and SUVs.

Planet Auto Wash's trained technicians transform dirty cars into shiny showpieces with phosphate-free Blue Coral products and burnished dressings. During the mini detail, a soft-cloth wash tenderizes the outer shell, sweeping grime and For Sale signs fashioned out of wet leaves from the surface while single-stage conditioner and triple-foam wax polish enrich the painted finish. Clear-coat protectants and Rain-X applications ensconce the car in a protective armor, and an air-dry brings the exterior to an arid glow. Staffers also venture inside, vacuuming the seats and tidying up the dash, console, and door jams. Tires and wheels also suit up in shine-boosting treatments. A spray-on body-gloss polish punctuates the treatment, and one of four car scents odorizes interiors, leaving cars with enough swagger to charm their way through tollbooths without paying.