After an inauspicious trial in the luxury car field, and recognizing the disappearing market for the single cylinder cars which made their reputation, Cadillac settled down with a design which had originated in 1906 (the 1907-1908 Model G). With in-house mass production of a single line, Cadillac was able to offer a high quality automobile at a moderate price: $1400 for the Model "Thirty" as compared to $2000 for the Model G.

Cadillac offered three models: 2-door Touring 5-passenger; 2-door Demi-Tonneau 4-passenger; and Roadster 3-passenger. The "Thirty" differed from the Model G as follows:

Bodies

• No closed bodies were offered.
• A detachable tonneau was once again available.
• It also had steel doors and cowl on the roadster and Demi-tonneau.
• Flared, twisted front fenders replaced the bulky flat fenders with filler between the fender and frame.
• Full running boards and running board dust shields were available on all bodies.
• There were no louvers in the hood.
• The bodies were finished (painted) by Cadillac

Chassis

• 3/4 platform rear spring system.
• Single dropped frame.
• Wheelbase lengthened to 2692mm
• In mid-year, brake drum diameter was increased to 304.8mm

Drive line

• Transmission refined and mounted at three points to frame cross members rather than at the four points to frame side rails.
• Universal joint was housed in the ball joint at rear of the transmission.
• Rear axle with bevel gear differential made by American Ball Bearing
• Engine
• Drive for water pump (gear type) and oiler changed from external belt to internal gears.
• Gear driven accessory shaft allows for optional magneto.
• Speed governor no longer used.