Please help me name this film..

[trentsteel]

Hello everyone,
please help me name this film I seen as a child in the 70's.
From what I can remember it starts off as a normal film with a boy in his bedroom (american) something flies into his window and then becomes a car. he jumps in the car and from what I can remember he drives the car through a door then he becomes a cartoon and starts an adventure.From what I can remember there is a dog also and somthing to do with the car being stuck in mud and the only way they can get out of the mud is to do maths? Please help me out as this is driving me insane.
Thank you.

[Euryale]

This possibly:

The Phantom Tollbooth (film) - Wikipedia, the free encyclopedia

E.

[dremble wedge]

The Phantom Tollbooth?

[jimw1]

[Steve Crook]

Hello everyone,
please help me name this film I seen as a child in the 70's.
From what I can remember it starts off as a normal film with a boy in his bedroom (american) something flies into his window and then becomes a car. he jumps in the car and from what I can remember he drives the car through a door then he becomes a cartoon and starts an adventure.From what I can remember there is a dog also and somthing to do with the car being stuck in mud and the only way they can get out of the mud is to do maths? Please help me out as this is driving me insane.
Thank you.

I think you'll find that the mud was when Milo got stuck in The Doldrums and The Letharges were trying to persuade him to be lazy like them. But Tock, his watch-dog woke him up and got him out

It is a great film, very clever

Steve