By 1910, touring cars were developing characteristic lines and shapes. Wings, which previously had been of wood and bent around the wheel to form a flat arch, were being replaced by domed steel wings. A running board, the length of the body, was replacing a rather untidy-looking step that had previously existed. Designers were also beginning to realise the variations of character that could be given to a car by subtle differences in body curves, particularly those of the wings, although these features were not really fully exploited until the 1930s. A shortcoming of many of the 1910 styles was that the horizontal bonnet had the appearance of running downhill towards the windscreen.
On some cars, therefore, there was a tendency for them to look as though they sagged in the middle. It was not as obvious on stubby cars such as the Model A Ford as it was on the larger and more-powerful cars like the 1907 Rolls-Royce Silver Ghost. Two steps were eventually taken to overcome this shortcoming. The first, and the most obvious one, was to run the bonnet uphill slightly towards the windscreen. The second step was to interpose between the end of the bonnet and the body a scuttle which was shaped to as to blend the form of the bonnet into the shape of the body.