Harder than you think, to answer. The larger heavier of the two would be the safest. But there's the small car nenesis, the dreaded suv and pickup truck, you're more apt to hit. This presents the question...Do you care more about the safety of you and your family or your wallet? Both small, you want cheap gas bills, despite your reason, raise your personal injury insurance. If you live you'll need it. The smart car...I don't relish the idea of being in a wreck and sitting up to my waist in battery acid for whatever amount of time, breathing hydrochloric acid fumes. The product of mixing lead and sulfuric acid for the power charge...For all the environmentalists what are they going to do with all that acid and lead when it's spent? So many of you would be suprised at the fuel mileage of a full size sedan and safety and comfort it provides after a 500 mile day trip. But...Don't take my word for it...You won't anyway.