I bought two of these, one for my wife and one for me. Neither would work. My wife has a Ford Focus and I have a Chevy Trailblazer. I drained the batteries down to about 8V, followed directions on the Mighty Jump and got absolutely no increase in voltage at the low batteries. I had to use my regular car charger to get the batteries back to full charge.
Save your money. At least the company I bought them from gave me credit for any other purchases without returning the units. BE SURE you have a warranty/guarantee if you do buy as you will probably need it.
Bottom Line: No, I would not recommend this to a friend