Panel 1: After having dropped Michael off at school, we find Elly thought-bubbling that John's car is different from hers because she feels as if she's level with the road.
Panel 2: She then notices that people are pointing at her and staring; she ascribes this to a sort of mystique associated with sports cars.
Panel 3: She decides to ignore their stares because it's not her fault that they've mistaken her for a rich, single, jet-setting executive oozing with confidence.
Panel 4: The joke ends up being on her because the person who was pointing at her tells the person driving the car that he or she wonders how long it will take that nitwit in the sports car to realize that she's got her skirt caught in the door.
Summary: Elly isn't stupid as such; she's just finding it difficult to deal with having to be aware of her surroundings. This failure to focus ends up being punctuated with a SCREEEEEEE-BANG!!!! Monday.
Of course, a lack of focus isn't just for soccer moms peeled out of their station wagons and plopped into Intimidationmobiles. It's also for dentists who don't know how to pack for themselves and also tend to forget to book hotel rooms.