One of the main things to look for in a new lens (or a hand-me-down lens), is Image Stabilization (IS for Canon et al, VR for Nikon). The lens name itself usually tells you whether the lens has this feature. The importance of this cannot be underestimated.
Without IS, the normal rule of thumb to follow with shutter speed is this: the slowest shutter speed you can use without your hand shaking is 1 divided by the effective focal length. Effective focal length refers to the 35mm equivalent focal length which in this case is 18*1.6 or about 29mm. (See my FAQ for more info on crop-factors.).
So without IS, the slowest hand-held shutter speed I would be able to use here would be around 1/30th of a second.
With IS, you can hand-hold the camera with much slower shutter speeds. For this shot, it allowed me to use a nice, slow shutter speed of 1/6th of a second which made the cars blur nicely in the background.