One automobile manufacturer has announced plans to increase

One automobile manufacturer has announced plans to increase the average fuel efficiency of its sport utility vehicles by 25 percent over the next five years, amounting to roughly five miles per gallon, and representing the first significant change in the fuel efficiency of any class of passenger vehicle in almost two decades.

(A) amounting to rougly five miles per gallon, and representing
(B) amounting to rougly five miles per gallon, and it would represent
(C) an increase that would amount to roughly five miles per gallon and it would represent
(D) an increase that would amount to roughly five miles per gallon and would represent
(E) which is an increase amounting to roughly five miles per gallon, representing

I think the answer is D. A cannot be correct because the word "to increase" needs to be represented in parallel by stating the two words "increase" and "represent" (which will be parallel). A and B both are missing the word increase or increasing. Amounting and representing are not the 2 parallel words... increase and representing are the 2 words that should be parallel. Having said that C and D are the closest and represent the correct parallelism. The only thing differentiating between the 2 is the word "it". I think "it" could mean the plan (plan to increase) or the actual increase. Hence D is the correct answer.