Kelley Blue Book names the BMW i3 the most fuel-efficient luxury car of 2015. BMW’s i3 tops this list for the second year in a row. According to the popular car guide, the i3’s design is modern and fresh, and truly stands out on the road. Not only is the i3 the most fuel-efficient luxury car, it’s the most fuel-efficient car, period. Adding a cure for anxiety is an available range-extending gas engine.

BMW i3 is followed by the 2015 Tesla Model S 70D and Mercedes-Benz B-Class.

2014 BMW All-Electric i3

BMW makes two variants of the i3 and the two cars look nearly identical from the outside and takes a trained eye to spot the differences. Just as the total ranges of the two models vary, the technical differences of the REx and the i3 BEV are rather dramatic. The i3 BEV can about 80 miles on a single charge, where as the i3 REx can travel about 150 miles on a full charge and full tank of premium gas.

BMW’s i3 REx weighs more at 3064 lbs compared to just 2799 lbs for the i3 BEV. 0-60 time for the i3 Rex is slower at 7.9 seconds vs 7.2 for the i3 BEV, purely because cause of the extra weight.

Related: BMW i3 One-Year Review

The MPGe goes from 124 miles for the i3 BEV to 117 miles for the i3 REx, but both are still way above Tesla’s S model and its 89 miles. Even the weight distribution changes from a BMW 48/52 front/rear for the i3 BEV to 45/55 for REx.

The range extender adds a 647 cc 2-cylinder motor from a BMW scooter that acts as a generator to charge the battery and extend the range of the i3. It is important to note that the i3 REx still uses an electric motor to move the car.