Bumper to Bumper is the text I have used in the classroom of the largest truck school chain on the west coast for nearly five years. I have recently had the opportunity to compare it to the other PTDIA endorsed workbook. Bumper to bumper presents more information, it is easier for the students to understand, the proofreaders seem to know a thing or two about trucks, there are very few mistakes. The other "PTDIA" workbook (what can I say they have the PTDIA logo on the cover) is useless compared to Bumper to Bumper. Naturally I have left my old employer as they have taken the less-effective, but much cheaper, text and done many other things that have lowered the quality of student training. Bumper to Bumper is the best text for the professional driver who wants to understand new developments in the industry too.