The car? Ah... if you mean that limousine, that's the one I chartered.
Literal
Car? Ah... that limousine [if-it-is-でしたら], I [subject-が] charter-[past-した] thing is-[polite-ですわ].
A refined, feminine conversational response. でしたら is the polite conditional of です ('if it is X') — more formal than なら. わ at the end is the feminine sentence-ender that softens and adds elegance — distinct from the emphatic masculine わ. Typical of refined/noble-lady speech in fiction. リムジン is a loanword. チャーターする is another loanword-verb ('to charter').