In Europe today, it's almost de rigueur to have a convertible-cum-coupe that has a folding metal top. Opel is the latest automaker to join the herd, with the Astra TwinTop. (Opel also produces the Tigra TwinTop, a small two-seater.) The car looks good, is very practical--there is a function that raises the folded top in the trunk to increase stowage--and is quite sporty, if you order the turbo model that uses a 197-hp 2.0-liter turbocharged in-line four. There are three other gasoline engines including a base 104-hp unit, and a 148-hp diesel. You may be shocked to learn that the attractive Astra is a cousin of the homely and uninspired Saturn Ion sold in the United States. GM promises that the next base Saturn will have more of the Astra's mojo. We hope so.