Mini Mark III and onwards ( 1970–2000 )

The Mark III Mini had a modified bodyshell with enough alterations to see the factory code change from ADO15 to ADO20 (which it shared with the Clubman). The most obvious changes were larger doors with concealed hinges. Customer demand led to the sliding windows being replaced with winding windows—although some Australian-manufactured Mark I Minis had adopted this feature in 1965 (with opening quarterlight windows). The suspension reverted from Hydrolastic to rubber cones as a cost-saving measure. (The 1275 GT and Clubman would retain the hydrolastic system until June 1971 when they, too, switched to the rubber cone suspension of the original Minis.)

Production at the Cowley plant was ended, and the simple name Mini completely replaced the separate Austin and Morris brands.

In the late 1970s, Innocenti introduced the Innocenti 90 and 120, Bertone-designed hatchbacks based on the Mini platform. Bertone also created a Mini Cooper equivalent, christened the Innocenti De Tomaso, that sported a 1275 cc engine similar to the MG Metro engine but with a 11 stud head, a special inlet manifold and uset the A clutch instead of the verto type. The most important feature was the utilization of homocinetic shafts, avoiding the rubber couplings.

By this stage, the Mini was still hugely popular in Britain, but it was looking increasingly outdated in the face of newer and more practical rivals including the Ford Fiesta, Vauxhall Chevette, Chrysler Sunbeam, Volkswagen Polo and Renault 5. Since the late 1960s, plans had been in place for a newer and more practical supermini to replace it, though the Mini was still the only car of this size built by British Leyland for the home market.

Reports of the Mini's imminent demise surfaced again in 1980 with the launch of the Austin Mini-Metro (badging with the word mini in all lowercase). In New Zealand in 1981, the Mini starred in a road trip movie directed by Geoff Murphy called Goodbye Pork Pie. The Mini was beginning to fall out of favour in many export markets, with the South African, Australian, and New Zealand markets all stopping production around this time.

Although the Mini continued after the Metro's launch, production volumes were reduced as British Leyland and successor combine Rover Group concentrated on the Metro as its key supermini. Indeed, 1981 was the Mini's last year in the top ten of Britain's top selling cars, as it came ninth and the Metro was fifth.

* Mark III (introduced in November 1969) had wind up windows with internal door hinges except for the van and pickup models. The boot lid lost the original hinged number plate and its recess shape and a large rear colour coded lamp was fitted in its place, along with larger rear side windows.

* Mark IV (introduced in 1976) had a front rubber mounted subframe with single tower bolts and the rear frame had some larger bushes introduced. Twin stalk indicators were introduced with larger foot pedals. From 1977 onwards, the rear indicator lamps had the reverse lights incorporated in them.
* Mark V (from 1984): all cars had 8.4-inch (210 mm) brake discs and plastic wheel arches (mini special arches) but retained the same Mark IV body shell shape.
* Mark VI (from 1990): the engine mounting points were moved forward to take 1275 cc power units, and includes the HIF carb version, plus the single point fuel injected car which came out in 1991. The 998 cc power units were discontinued. Internal bonnet release were fitted from 1992.
* Mark VII was the final twin point injection with front mounted radiator.