some trucks use propane to increase their 'MPG' (although that here is a bad term... ) has anyone ever tried it in a Barth???

.....anybody know anything about this/

Propane injection in a diesel is a bit like nitrous oxide in a gas job, it increases the combustion efficiency of the motor. The danger in increasing efficiency is in the unknowns concerning the ability of the engine design in handling the added performance and/or heat generated. I've only heard good things about propane injection as opposed to the many horror stories with nitrous, so maybe it's not a real concern.