I just finished a 4k mile trip with the BD and was disappointed with performance and economy. It has 4 modes; Stock, Tow, Performance, and Extreme. Initially, I kept the same mode from fill up to fill up and generally filled up between 1/4 and 1/2. I drove mostly at 65 mph, all interstate; TX, AR, TN, VA, KY, back through OK and home to TX, using the cruise control most of the time. There were hills, but nothing big. I was towing my 36 ft travel trailer weighing about 10.5k pounds. In Tow Mode, I noticed no improvement in power but there was a little mpg improvement; less than .5 mpg. I noticed no difference between the Performance and Extreme mode, but did not keep it in Extreme for a full tank. With these 2 modes, I did notice a little 'seat of the pants' power and mpg improved about .5 mpg. After that, I started changing modes about every 100 miles and there was no difference between Stock and Tow, and none between Performance and Extreme. MPG by the gauge stayed about 10.5 for all modes. When I made this trip last year, the gauge was a little above 10. It does have a 30 day full refund, return policy, so I've contacted the seller for an RMA and will be sending it back within the next couple of days.
Now, I'm looking for another tuner.
Now, I'm looking for another tuner.