Ex hire is probably the equivalent over here. From my (admittedly smallish) experience then company/pool cars are kept way way longer than in the UK. Hence there isn't that big release of 1/3 year old cars through the auctions.
The comment about dealer volume discounts is true. Hence the 'pre registered' cars you see advertised (in the UK). They are cars that the dealer has bought themselves to notch up a sale.
But really, I'd get here, buy a used car for 6 months and get to understand what you really want before considering new. It won't be the same car you have in the UK. The different roads,joourney types, right through to the size of other vehicles and parking spaces means that what was perfect in the UK wouldn't work here.