One of the most important ideas in Pixar's first Cars film was to not have the headlights of the cars be their eyes, which is the most typical design you'll see when cars are anthropomorphised, but instead to put the eyes in the windshield.
There is precedent for this. Disney themselves made Susie the Little Blue Coupe, a cartoon that used this style. But the effects of the decision are notable. For one thing, it stops the car seeming creepy and snakey and low down. For another thing, it makes pretty much the whole body of the car into the whole body of the character; it doesn't force the head down real low.
And now, it also means there can be a consistency of design for other vehicles that don't have headlights. For example, planes. The planes in Planes also have eyes in their cockpit or windshield, maintaining a consistency with the Pixar films.
I don't know if John Lasseter was thinking of spin-off stories with other vehicles when he made the first film, but he certainly made it possible with that one instrumental choice.
Here's the latest trailer for Planes out of New Zealand. Note how the planes' own distinguishing feature, the propeller, tends to play as something moustache-like.
We'll be seeing Planes very soon. We've heard good things, and it's certainly encouraging that Disney decided to bump it up from a straight-to-video release to a full on theatrical roll out, on August 9th in the US and August 23rd in the UK.
And yes, despite the slip-up in our official Twitter feed, we're fully aware this film is from Disney Toon Studios and not Disney.