What drawing style are the esurance characters? Actually, more specifically what drawing style is this Gorilla?
It's a vector drawing .
Vector graphics is the use of geometrical primitives such as points, lines, curves, and shapes or polygon(s), which are all based on mathematical equations, to represent images in computer graphics.
This character could be created with the help of Illustrator or Inkscape.
See this link for more information on character formatting...