It's been hard for me to ignore a significant change in fuel economy in my vehicle, which happened to correspond to using FP3000. The increase also corresponds to higher temperatures, which is associated with Air Conditioning compressor use, which I would expect to decrease mpg. Anyway, I track mpg on each and every tankful of fuel, and I've put 32,500+ miles on my Subaru since September, 2006. MPG stays right around 30 mpg, with a mixture of mostly highway, but almost always some city/rural driving. Once, into about a 50 mph headwind, at near-freezing temps, and running 75-80 mph, I got 25.something. A few times, in the opposite conditions, running 70-75 mph, I got around 35 mpg.
Recently, driving the same routes, at the same speeds, but at warmer temps, I've been consistantly getting 34-36 mpg. The vehicle is rated at 30 mpg highway, btw. And, it's supposed to have it's spark plugs changed at 30,000 miles. I've always used FP60 until I started using FP3000, and I removed a plug to check it's condition...put it right back without even cleaning it...it is clean with the correct gap. I figure with the mpg the way it is, and that one plug looked so good, the rest must be OK, too. I also wonder if my car was just a bit "tight" at first, then we hit the "winter fuel", and now with a "run-in" drivetrain and summer fuel, those variables might play a part in the increased economy.
I wonder if I'm "drafting" behind trucks more than usual...that would increase the mpg. I also wonder if FP60 and FP3000 are contributing to the spark-plug cleanliness, and if FP3000 is helping fuel economy. Way too many variables to be able to determine the cause(s), but, the last 1500+/- miles have shown a distinct improvement in mpg.
Whatever the factor(s) is(are), it's significant.
