The Austin-Healey 3000 was announced on 1 July 1959 with a 3-litre BMC C-Series engine to replace the smaller 2.6-litre engine of the 100-6 and disc brakes for its front wheels. The manufacturers claimed it would reach 60 mph in 11 seconds and 100 mph in 31 seconds.
Other changes were minor compared to those between the original 100 and the 100–6. The wheelbase and body were unchanged as were the body-styles, a 2+2 or BT7 and a two-seater BN7.
Weather protection remained minimal, a folding plastic roof on a light demountable frame and above the doors detachable side screens holding sliding perspex panels. Wire wheels, overdrive gearbox, laminated windscreen, heater, adjustable steering column, detachable hard top for the 2+2, and two-tone paint were available as options.
13,650 Mark Is were built: 2,825 BN7 open two-seaters, and 10,825 BT7 2+2.