I've got a commander too, so I see both sides. This weekend, took the family in the cherokee instead. It is much faster for sure.
A word on brakes. My mileage went way up around the same time before I replaced my front caliper, pads and rotors. The grinding noise of my front brakes was so bad that I was not hitting the accelerator all the way up to the stop sign (and then slamming on the brakes). So, I learned to avoid the grinding noise by using the brakes less, and not annoying the guy next to me when he would hear my brakes screech.
Of course now the screech is back with new pads and I am going to have to take them apart next week to put the blue glue back on again to get the squeel out.
But not riding my brakes caused a major boost in fuel economy because I was using my brakes AND gas less, by not riding on the gas as much.
There is no doubt that the Lucas stuff made a MAJOR difference for me. Going from 23 to 25 doesn't sound like a lot, until you figure I rack up 2500 miles a month. At these prices, the bottle of lucas pays for itself.
Not to mention that the engine sounds and runs better.
The trick that the guys at the parts store taught me is get one of the small individual bottles and also the biggest one they have. Then, you just refill the individual one with each tank.
It's only 30 dollars for a jug, and by my calculations that should get me through at least 20,000 miles.