We have just sent 2 each from both of our phones and won feck all.
It's a good publicity stunt IMO. Whats the difference, they have £100,000 prize fund, so it doesn't really matter if they give away a £100,000 car or 9000 prizes of £10 and 1 of £10,000 as they are. It hasn't cost them any more, but its a bit different.