Water thrives when under pressure, much like spelling-bee finalists and fast-food drive-thru operators at the Indy 500. Unleash pressurized power with today's Groupon: for $27, you get three "The Best" car washes with Tire Shine at Shield System Car Wash (a $60 value). This Groupon is valid at the Billerica, Brighton, and Winchester locations.

Shield System Car Wash's three locations peel off automotive filth with soft cloths before slathering vehicles with shine-enhancing layers of foam, wax, and sealant. The five-minute wash whittles caked exteriors down to the original shape and showroom shine with triple-foam soaps and underbody rinses. Wheel and rim are cleansed with Tire Shine, plucking debris from car's lower extremities before applications of Shield sealant and Shield vivid wax glaze the car shell to give it a smooth, shiny veneer. Finally, doses of Shield ultrashine sealant cling to the finish to defend its sparkling luster against dirt and hitchhiking paparazzi.

Drivers visiting a Shield System shop can recruit Billerica's self-service shampoo/turbo vacuums to ward off any mysophobic car thieves that might be lurking nearby.