The gran coupe, with its two extra doors, is 6 inches longer overall and offers more rear head and leg room, but the standard full-length console makes five-passenger seating awkward even in a pinch. It's best to think of these cars as roomy four-seaters with grand-scale performance and appointments.
Packages are available to help buyers personalize their cars with extra-cost woods, leathers, and colors (both inside and out). Interesting options include 4-wheel steering, glazed ceramic interior controls, automatic soft-closing doors, and a BMW-issue ski bag.
The 650i's natural competitor is the Mercedes CLS-Class, which offers a twin turbo of its own, albeit with 402 horsepower, and a somewhat lower sticker price. Porsche's 4-door Panamera is priced similarly to the gran coupe, but is skewed more toward all-out performance than high-class touring. Some lower-rung players (Audi A7, Mercedes E-Class, Cadillac CTS) can be optioned well enough to be credible alternatives for buyers who want something more conservative in looks and price.