I drive several cars and trucks but i use HHO mostly on my 2000 Cavalier. After playing with a few gen.s i had one working really well, for a while. I drive to and from Memphis Tn. from here in Georgia, every other weekend to visit my son (1460 miles in one weekend!). I get to test alot. In Alabama there's alot of construction and their Interstate speeds are 55 mph on 2 lanes, then they go 70 mph on 3 lanes. Well in coming out of that merge i went from 55 to 85 so i could cruise there, but my car didn't want to level off when i let off the pedal. It kept going all the way up to 105 mph when i shut off the HHO gen. ! I was puzzled at first and pulled over on the Interstate to see what was wrong. Turns out i had a leak and my gen. was boiling, cracked and almost empty. At first i thought the increase in speed was the vacuum leak that was created by the busted gen., but that wasn't so due to the safety valves that i have in place when excess vacuum is detected. So i'm not sure how i got so much power out of that either!
We took a trip to New York as well last year in my 4 wheel drive Suburban, only used the gen. on the way home. Got an increase of 1/3 the mileage! Had people driving on the Interstate in South Carolina taking pictures of my unit on the front of my truck while we were driving. Its came a little ways along since.