in all fairness, I don't think I have enough data to tell. Looking at the numbers, it doesn't give me a warm fuzzy considering what the product cost. But check them out plotted.
Also, the average economy over all for not using FP from the beginning is 19.58 mpg vs. 19.86 mpg with FP. So by that reckoning FP isn't hurting mpg. But,
There's a lot of variables that have a far greater impact- driving style, gasoline quality, where you're driving, weather and time of year especially, which all have an order of magnitude greater influence on economy than FP. I've also swapped thermostats between 160 and 190 over the past 2 years, changed spark plugs, engine oil weights, tranny and differential oils.
But for what difference I have now, for a 0.25 mile per gallon increase in economy how far do I have to drive and how much gas do I have to buy to make my money back:
if FP costs $35/gal not incl shipping or tax,
at 20mpg without FP and with 20.25mpg with,
after 20000 miles of driving, 20mpg = 1000 gal gas vs 20.25mpg = 987.6 gal gas. That's a savings of just 12.4 gallons, and at $2/gal that's roughly $25. At $3/gal it's $37. If you gain 0.5mpg with FP, that cuts it down to 10000 miles.
[ September 02, 2005, 02:06 PM: Message edited by: 1 FMF ]