He was instructed to design a car that would seat four, be the smallest car that the corporation currently made and use an existing engine. The Mini was given the A series engine already used in the Morris Minor and Austin 35 thereby making economical use of existing parts. The only difference was that it was mounted sideways in a very clever arrangement with the gearbox in the sump driving the front wheels. This design has been taken up by pretty much every car manufacturer worldwide to this day.

Over 41 years of Mini production from 1959 to 2000 the Mini can be divided up into 4 basic major design changes: The Mini Mk1 from 1959 to 1967, the Mini Mk2 from 1967 to 1970, the Mini Mk3 from 1970 to 1976 and the Mini Mk4 from 1976.

This divides Minis up into the major body shell design changes.

Mini Mk2: Wider rear windscreen and different shaped radiator grill.

Mini Mk3: Larger doors, wind-up windows and internal door hinges.

Mini Mk4: Rubber mounted subframes.

As far as Mini spares are concerned the Mini is very versatile and lends itself very much to DIY maintenance because of its basic design, economical cost of Mini parts and huge choice of aftermarket Mini parts and Mini accessories for modification. Because a lot of basic measurements and designs have not changed over the years many Mini spares are interchangeable between the marks and years of Mini production.

For example, the basic measurements for the Mini engine mountings and Mini subframes have remained the same allowing engines to be swapped between Minis of different years. The Mini seat mountings have stayed the same since 1962 allowing any Mini front seat and extended Mini seat brackets to be fitted to any car and goodness knows how many versions of Mini seats have been designed over the years. It is also useful for any Mini DIY enthusiast to know that the most used thread size of Mini nut/Mini bolt/Mini set screw for the average Mini part is 5/16 inch UNF. The 1/4 inch UNF thread covers the smaller Mini spares and the 3/8 inch UNF thread is for some of the larger Mini parts. There are of course other sizes for less numerous Mini spare parts. These are all imperial measurements. Metric threads were not used with the exception of, for example, Mini brake pipe unions on the GMC227 Mini dual circuit brake master cylinders introduced in 1985 and some after market Mini spares. The Mini rear subframes, Mini rear suspension and Mini rear brake parts have mostly remained the same throughout the 41 years of Mini production. There were two basic Mini engine designs over the life of the Mini. These were the original Mini A series and the Mini A+ series engines. The Mini A+ series engine was introduced in 1980 and was really a hybrid of the Mini A series engine built as a stronger version. The Mini cylinder block and Mini cylinder head were heavier castings. Again many of the basic measurements were kept the same allowing, for example, Mini cylinder heads to be interchanged between Mini cylinder blocks. The Mini engine capacities were 848cc, 997cc, 998cc, 970cc, 1071cc, 1275cc and 1098cc.

Apart from the Mini saloon there were also other models which included the Mini Cooper, Mini Cooper S, Mini Automatic, Riley Elf, Wolsey Hornet, Mini Van, Mini Pickup, Mini Moke, Mini Traveller, Mini Countryman, Mini Clubman, Mini Clubman Estate and Mini 1275 GT. There were also numerous other Mini models and Mini limited editions. For example: Austin Seven Mini, Mini Super Deluxe, Mini Special, Mini HL, Mini Mayfair, Mini Sprite, Mini 25, Mini 30, Mini 40, Mini Sky, Mini Red Hot, Mini Racing Green, Mini Racing Flame and a great many more Mini models.