mm, or possibly cm
Whats the most widely reported measure of inflation?
Liters, most kitchen sinks are more than one or two liters
Liters are the SI unit of measure for volume. Liters are most often used to measure the volume of liquids and gasses.
The answer depends on what you wish to measure: its length (or width or height), its mass, it fuel efficiency, it maximum speed, its maximum acceleration, its tightest turning circle, its power output, its drag, etc.
your audience and purpose
The most appropiate thing to say would be "congratulations".