the problem with the 18-55 canon kit-lens is its too soft, no matter what f stop you shoot at.... really noticable ∞ focus shots, or high depth of field shots. the lens 'works' best IMO for close subjects, and not 'wonderful' for cars... but ok enough for now
i'm shooting for a 10-22 as its' moral replacement in my arsonal; eventually, my ideal package would be this : (expensive)
wide-angle
EF-S 10-22mm f/3.5-4.5 USM
general purpose
EF 24-105mm f/4L IS USM
telephoto
EF 100-400mm f/4.5-5.6L IS USM
... in an ideal world anyway... before moving on to further options