If she wants a convertible, and to be honest I can really see the attraction, you should maybe consider the Mitsubishi Colt CZC, they don't look good with the roof up, but I'd bet that they are a way better car than the a Ford Ka. The roof is a hard top too, if security is a problem. I've got a Mitsubishi Colt CZ2 as my commuting car, honestly I can't fault it at all. Its a bit dull, but handles well, and is so reliable. Other than that a Corsa or a Peugeot do a small one too, I'd rather have a Mitsubishi though, just imagine that they are way more reliable. The Colt is cheap too.