Put 1 1/2 tsp of vinegar in a measuring cup then top it up to the half cup mark with milk. (365daysofeasyrecipes.com)
Place maple syrup in a 2 cup measuring cup and fill to the 1 cup mark with milk. (takeamegabite.com)
Cons: Armrest placement awkward for trip comfort, suction cup marks on windshield, handles rough pavement poorly, wind noise very noticeable at highway speeds, outside rearview mirrors block side views. (autolist.com)