1st, i did the test and plenty here have.

2nd, u will save only like around 20 miles per full tank.

3rd, It's not safe for ur car, u can end up braking something in the long run.

it did not hurt my car, but i wont recomand, i was told its bad for ur VX. Ands its not a awd but 4wd all the time, just like the land cruiser. all u have is dead waight. but yes u will save, but not 2 much.