Elmer’s new car gets 50 \% better fuel efficiency, measured in kilometers per liter, than his old car. However, his new car uses diesel fuel, which is 20 \% more expensive per liter than the gasoline his old car uses. By what percent will Elmer save money if he uses his new car instead of his old car for a long trip?

**Answer Choices**

A. 20 \%

B. 26 \dfrac{2}{3} \%

C. 27 \dfrac{7}{9} \%

D. 33 \dfrac{1}{3} \%

E. 41 \dfrac{2}{3} \%