Steve
Obviously you're losing sleep (nothing to do with the little one..) over the GTD/GTI choice, you need a few more reasons to persuade the logical part of your brain. (and the wife)
Junior will appreciate the rattles in his cot but not the rattles in the car.
Young children like tractors - he might get confused.
When he watches you fill up at the petrol station he won't think 'why didn't daddy use the nice green one'.
He won't see the sad look in daddy's eyes when he sees a GTI.
He won't worry about daddy's car smoking too much.
When he's old enough he'll brag about you to his mates.
