Upgrades included more interior space, improved brakes, rack and pinion steering, increased suspension travel, and telescopic shock absorbers instead of the older lever arm design.

The interior was made more comfortable for taller drivers by moving the engine, firewall and dash forward to give 3 inches (76 mm) more legroom.

The optional C-Type cylinder head carried over from the XK120 catalogue, and produced 210 bhp (157 kW) gross at 5750 rpm.

When fitted with the C-type head, 2-inch sand-cast H8 carburettors, heavier torsion bars and twin exhaust pipes, the car was designated XK140 SE in the UK and XK140 MC in North America.

[2] The OTS, (Open Two Seater) or Roadster as it was designated in America, had a light canvas top that folded out of sight behind the seats.

Like the XK120 Roadster, the XK140 version had removable canvas and plastic side curtains on light alloy barchetta-type doors, and a tonneau cover.

The door tops and scuttle panel were cut back by two inches (50 mm) compared to the XK120, to allow a more modern positioning[clarification needed] of the steering wheel.

Production cars had the roof lengthened, windscreen placed further forward, shorter front wings, and longer doors, all resulting in easier entry and more interior space and legroom.