1. You need a 5 door
2. It needs to be Focus size or above
3. It will be over 10 years old
4. Diesel?
5. You might struggle.
I'd seriously consider a Mondeo (but the diesel is not fast) or a 306 (XRDT/XTDT) but a big old Merc? It'll be pricey when the auto 'box needs work. Or the head gasket goes. Or a window motor packs in. In a rain storm. When it's raining. And it's open.