Peter Ruff and the Double Four by E. Phillips Oppenheim

Westward sped the little electric brougham, driven without regard to police regulations or any rule of the road: silent and swift, wholly regardless of other vehicles -- as though, indeed, its occupants were assuming to themselves the rights of Royalty. Inside, Peter Ruff, a little breathless, was leaning forward, tying his white cravat with the aid of the little polished mirror set in the middle of the dark green cushions. At his right hand was Lady Mary, watching his proceedings with an air of agonised impatience.

"Let me tell you -- " she begged.