2004 Navigator Get 19.5 MPG !!!

[Christ]

Lowering shouldn't really be all too difficult, but you'll be dealing with air-ride... LRR tires, IMO, still aren't worth what you pay for them, especially in larger sizes, especially when you compared them to any "perma-mod"... LRR tires are great, but they only last until the tire is dead, then you're out another $1000. Not exactly economical, when you can get a good, hard, standard tire w/ a 50k mile warranty for like $125 (for larger sizes), then use the extra $400 per set of tires to pay for things like fuel, and other mods.

Driver modding is by far the best thing you can do... anything you can do to just drive more efficiently will help the most of anything, and will show greater returns on other things you do.

I recommend a full belly pan along w/ the grille block.

[rogeco]

I'm late to the game, but will support the comment that lowering a vehicle with an air-ride is not that hard. In fact, Ford has a factory kit for this. It includes 4 new dampers, 1 pair of springs (front) and a sensor relocation bracket that causes the rear to lower. I can't recall the price now (700ish), but it was well under 1000. If you wait until you need new shocks anyway, it's effectively pretty inexpensive. Haven't done mine yet, because the stock shocks are working remarkably well at 105,000miles, and because >95% of my use is for towing, where lowering and roofracks would affect little. Just fyi

[rogeco]

Btw, I've got (non towing app) up to about 19.5mpg with careful towing too, but there was a bit of drafting involved. 18 is as good as I can get truly solo.