Go for the 630i. It's the cheapest model and has the smallest engine, but its 3.0 V8 takes you to 60mph from rest in just 6.5sec. It burbles nicely when worked hard, but otherwise does its work quietly, with either a six-speed manual or auto gearbox.
Its interior may not have quite the special sense of occasion that its big brother, the M6, conveys, but it is still trimmed in leather and has pretty much all you'd ever want, although sat-nav is an extra.
Like all Sixes, it comes in a choice of standard or Sport trim, the latter bringing stiffer suspension and bigger alloy wheels. We prefer standard models for their more absorbent ride and subtler looks.
If you can bear the expense of buying and owning, the other options are the 650i and the M6, which produces 500bhp and screams to 60mph in under 5sec.
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