AFAIK, sometimes the manufacturers will offer very good deals on specific models for different reasons which mean that you can end up paying less than depreciation:
-New model, desire to get it out and "seen" on the road; leasing gets a decent number of them being driven about quickly
-Old model, want to shift stock before bringing out a facelift version
-With new models they'll also sometimes offer very good deals (especially on shorter e.g. 2 year leases) specifically with an eye to them ending up in the second hand dealer network a couple of years later...
You also have to remember that the depreciation number than a consumer sees (what they pay-what it's worth at the end) isn't the same for the manufacturer as their profit is built in there. It's not that they make no profit on one of these deals, it's just lower than for someone buying the car outright at list price.
They can also be much cheaper to supply through a lease - mostly you don't use a main dealer but an online/phone only, low cost company so the costs of selling are lower.
For example though, my husbands last car. List price on it was £33k (give or take a couple of hundred). Over two years we paid £250pcm, plus the deposit was £2k. (this was a bit flash too, my husband is very in to cars!). So total cost of £8k.
A 2 year old, according to Parkers, will fetch somewhere between £18500 (PX) to £20900 (selling to a dealer)
If we'd owned that outright the depreciation would have been somewhere between £12k-£14.5k, plus we'd have had servicing costs on top of that; call it another £500 as the services weren't cheap but I can't remember the exact number. That's also assuming we had the cash to buy it (so not allowing for any interest costs) or not allowing for any loss of interest on savings if that's where the money had come from.
The previous car worked out to be similar.
Yes, of course we could have bought second hand and so on, but this shows the depreciation example