within our cylinder piston reciprocating motion to power the car. This process is the displacement of the piston swept volume, that is, the effective volume, while the cylinder volume refers to the total volume of the cylinder, the cylinder volume is actually larger than the displacement (larger question as to why emissions figures, it is because of the displacement of logical rounded, you can not write a displacement is 1.998 liters of it). We know that the car is a work by burning a fuel, the fuel must first be compressed in the cylinder, and then instantly expansion of the combustion outline power.
Compression
than the average car is probably again about 10: 1, can be understood: the cylinder volume 10 is here, and that is an invalid volume, and the difference between them is 9 displacement. If we compress the volume of fuel is zero, then it is equal to the volume of displacement, and this is impossible.