Registration is now open (log into your Discover account first) for the Discover it cashback bonus categories of "Gas & Ground Transportation" for the first calendar quarter of 2016.
You'll earn 5% cash back on up to $1,500 in purchases in the bonus categories, and if you registered in time for the Discover it double cash promotion you'll earn the same amount again after the end of your promotional period.
This is a terrific offer if you have access to PIN-enabled prepaid debit cards at gas stations or convenience stores coded as gas stations, but if you don't have access to those at home (or while on the road), you still might consider using the bonus category to add value to any transportation passes or rail cards you plan to use throughout the year. And of course, 5-10% cash back on gas purchases isn't terrible either.
However you plan to use it, be sure to log into your Discover account and register now, before you forget.