when i first joined the scheme speed was important as the car i had was on its last legs. at the time i needed to be able to lug a lot of kit around so wanted a large suv almost van like space.
citroen had the grand picasso 7 seater and the dealer was able to pull up a list of what specs and colours were on the next boat accross the channel. in the spec i wanted i was restricted to a choice of 3 colours but got the car in 14 days. not sure if thats possible now but you can but ask.
draw up a shortlist of models and specs you would like and ask the dealers whats about just be prepared to compromise.