NOTE: This episode was never actually animated fully, but the completed script is availible for download at missionhill.tripod.com.
It's really a shame that this episode was never produced. It is a very good example of the overall humour of the writers. Everyone is in character and you can just imagine the way everything would look and sound as a finished episode.
The way that the power struggles in the car were portrayed was very funny. Kevin's eagerness to visit grandma and Andy's eagerness to do just the opposite are both very true to the established behaviour of the two, as is Posey's desire to dance in a field of sunflowers. The twist in the ending was just perfect.
Overall the writing of this is superb, and it may be my favourite Mission Hill episode. Definately worth the read.