My 85 Civic Wagon DX did one better, you could fold the cushion over and fold the seatback down flat, but if you needed even more space, the back seat cushion folds over again so it's upside down and level with the seatback, so you've basically added an extra foot.
All seats up:
p _/ _/__
Rear seats down, cushion flipped forward
p _/,___
Rear seats down, cushion flipped upside down:
p _/____
Oh and as an extra bonus, lounge mode:
p ___/__
Anyway, I had a look at the Elantra today, very nice car even in the GL trim, I'd be very happy with the GL trim.