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} \%