The egg is the largest cell in the human body and contains a high amount of water. When the egg is frozen, the ice crystals that form can destroy the integrity of the cell. To prevent this, the egg must be dehydrated prior to freezing.
A slot car (sometimes, slotcar) is a powered miniature auto or other vehicle that is guided by a groove or slot in the track on which it runs.
The bottomline is that there is no best slot car scale. If you want to get involved in organized race events, check out hobby shops and slot racing organizations in your area to find out what scale is most popular, most prevalent.