Running a 2005 Excursion PSD on Bio. Here is what I have so far. At 15k miles I started using Bio in small blends. I have no programmer mods, just a 4" exhaust. My freeway mpg at 75mph was 18mpg on #2 alone. Running B5 I got 19.5mpg at 75, and at B10 I got 20mpg at 75. Best mileage was on B20, got 21.5mpg at 75mph. Currently running 50% (B50) and it has dropped to 17.5mg at 75mph. I assume, and have read, that anyting over B20 decreases mpg for an assortment or reasons. That said, I find it very difficult to fathom 48mpg on SVO/WVO! Chemistry does not seem to support that figure but it would certainly be nice. Check with your friend and find out more specifics.