Most of Rolls' clientele preferred more powerful vehicles than the 10 hp and 15 hp and
decided in favour of a Rolls-Royce 20 hp or a 30 hp. The 30 hp offered six-cylinders, a
development which was new not only to Rolls-Royce but to the automobile industry as a
whole.

A severe problem occurred with torsional flexibility of the crank-shaft, a condition which
was exacerbated as engine length increased. The problem afflicted the six-cylinder engine to the
extent that crankshaft failure occurred. Royce became aware of these difficulties during test
runs at the factory, and, although he could only incorporate slight changes, this trouble never occurred
with a car when in the hands of a customer.

A Rolls-Royce 30 hp was entered for theScottish Reliability Trials 1906 and the car emerged victorious.