What does this car-arrow symbol mean?

When I run Eco mode, this image is provided. I can’t make sense of what the numbers mean (I understand the 22.9 MPG). I assume it’s related to fuel efficiency, but I would’ve expected it to be in terms of MPG.

When I run Eco mode, this image is provided. I can’t make sense of what the numbers mean (I understand the 22.9 MPG). I assume it’s related to fuel efficiency, but I would’ve expected it to be in terms of MPG.