That's a fun puzzle. I converted the code to C# and managed to get a 20x speedup. Not sure how the code would fare in Java, but I presume that things that are slow in C# are probably also slow in Java.
PHEV vehicles seem incorrect. The Toyota Rav4 Prime has a range given as 42 miles, which is true for electric only, but it also has between 400-500 miles of gas range.
After playing around a bit, all the make/model/year drop downs are empty and I can't get them to work again.