2010 Rolls-Royce RR4

As opposed to the Phantom which has a purpose-built, aluminum structure, the RR4 is based on the next-generation 2010 BMW 7-series, with a primarily steel body and some aluminum to keep total weight close to 5000 pounds.

The RR4s engine is new and unique to Rolls-Royce, the BMW-owned automaker claims.The RR4 will be longer, wider, and taller than the standard 7-series and will ride on a longer wheelbase. It will be recognizable as the Phantoms little brother, with the same slab-sided bodywork, a high beltline, tapered rear, ample rear-seat legroom, coach-style rear-hinged rear doors, and Rolls-Royces trademark waterfall grille.

The new 7's "F01" platform will be pulled like taffy to make the RR4 longer, wider, and taller than its German cousin. The Rolls will also have a longer wheelbase than even L-model 7s--a majestic 138 inches, according to one British report. Mustn't skimp on m'lud's rear-seat space. On the other hand, the RR4 will be almost a compact next to the Phantom--over a foot shorter by some accounts. It's also said to be nearly 500 lb lighter despite a structure that uses less weight-saving aluminum. Still, the RR4 will be no bantam, likely to tip the scales just north of 5,000 lb.

The company said early on that the powerplant will be "exclusive to Rolls-Royce," and some think that rules out a BMW engine. On the other hand, "exclusive" could just as easily mean a Rolls-only version of a BMW engine. Another complication is the RR4's place in the world. In terms of power and performance, being "upstairs" of the 453-horsepower 6.0-liter V12 Phantom just wouldn't do, but that would leave RR4 conspicuously "downstairs" of a prime competitor, the 553-horsepower 6.0-liter W12 Bentley Continental Flying Spur. In addition, the Phantom has been roundly criticized for its prodigious fuel thirst, and Bentley has announced plans to reduce fuel consumption and CO2 emissions for all its cars, which puts pressure on Rolls to follow suit.