Well, like any hollywood show, I assume they take certain \'liberties\'. They surely exagerate the HP, and speeds, possibly the ages a bit (but a 15 year old who has been boosting cars for two years, can prolly drive an automatic fairly well). However, as for the final shot being fake... I understand that one.
The chase car who\'s camera we have been watching is out of the chase. The host then said that \'a few miles later, [the 15 year old] had to give up, because of car trouble\'. If they don\'t have the footage from that car (remember, the police officer or station has to voluntarily send it in), then they would be forced to either not show that ending or take the convenient almost-stop from earlier in the chase.