I think this can be summarised as a year's extension to the deadline for mandatory replacement of "old technology" cars, whatever that means. The definition seems to be based purely on date first registered.
Cars first registered before 31/12/2001 must be replaced before 20/12/2015. Last year the deadline applied to cars registered before 31/12/2000.
So, it's not really an extension at all is it? I'll say now, I know nothing about this at all. Just reading the link............
There are also a number of changes to the need to submit an E9 property declaration within certain time limits if you buy,sell or transfer property. If this is you, I would suggest consulting your accountant quite soon.