Most modern engines (but not all), including those fitted in the MINI, work on the 'four-stroke cycle'. Each cylinder within the engine goes through four distinct phases of operation, called strokes.

These are:

• Induction stroke - The piston starts at the top of the cylinder, the intake valve opens, and the piston moves down, drawing in a cylinder-full of air and fuel.
• Compression stroke - Then the piston moves back up the cylinder compressing and heating this fuel/air mixture. Compression increases the power of the explosion.
• Power stroke - When the piston reaches the top of its stroke, the spark plug emits a spark to ignite the fuel/air mixture. The fuel/air mixture in the cylinder rapidly expands, driving the piston down.
• Exhaust stroke - Once the piston reaches the bottom of its stroke, the exhaust valve opens and the exhaust gases are pushed out of the cylinder as the piston rises.

This four-stroke cycle also applies to diesel engines, but rather than a spark plug igniting the fuel, high temperatures within the cylinder, caused by increased compression ratios, ignite the fuel/air mixture as soon as the diesel fuel is injected.

Power from a car's engine is converted into movement of the wheels by the powertrain, the name given to all the parts of the car, such as the gearbox, transmission and differential, that work together to make the vehicle move.

All cars have a transmission system – its job is to take engine power and transfer it to the wheels. One of the elements of this is the gearbox. But why do we need it and what does it do? Think about a bicycle and a cyclist. If you compare a cyclist to an engine in a car, then the legs represent the pistons, and the pedals the crankshaft. Power is transmitted to the rear wheel by a chain, from the main sprocket that is turned by the pedals, to another smaller cog, fixed at the centre of the wheel. One complete turn of the main sprocket may result in two turns of the smaller cog on the rear wheel. This would give a gear ratio of 2:1.

This ratio may be fine on a flat surface, but it would be difficult to ride up a hill in this gear, or get moving from a standstill. Bicycles, just like cars, need to be able to change this ratio, i.e. change gear. On a bicycle you can change gear by moving the chain to different sized cogs on the rear wheel. A manual transmission on a car works in a similar way by moving the gear lever to select different sized gears.

In a car with a conventional manual transmission, the link between the engine and the gearbox is the clutch. It can be engaged and disengaged by depressing the clutch pedal. When it is engaged it allows engine power to pass into the gearbox. In a MINI, power is relayed through the differential to drive shafts that are connected to the front wheels.

The differential relays power to the road wheels via drive shafts on the MINI. The differential allows both front wheels to rotate at different speeds. This is something they have to do when they are going around corners because the inner wheel will turn more slowly than the outer, as it has less far to travel.