I didn't really read it as necessarily "problems" running on LPG dual-setup, just not as efficient as an engine configured specifically to run only LPG. I agree with you, this technology has been around for quite some time. Most of the citrus grove owners around here have their trucks setup for LPG, not for economy but to keep people from stealing the gasoline or diesel from them. You can always tell when you're behind one! ;pg;