Originally posted by rustednuts:
I get better mileage using lower octane gas. Tried several times with the high octane and got around 21 mpg. Not sure how that works either but it does...
That's interesting. Most my vehicles don't seem to care what grade of fuel I put in them, so I buy what's cheapest.
But on a recent trip I tried hard to maximize my mileage, and the car I took does get about 10% better mileage on mid-grade gas than on regular, and doesn't seem to improve at all with the top grade. I tested this over about 10 days and nearly 3000 miles of mostly highway driving and it held true.
So I figure a 2-3% increase in cost to go 10% further is a good idea. But only in the one car. Running about local it doesn't make quite as much difference. I average 20.something instead of 19.something, or about 5% better.
My '89 K3500 gets terrible mileage no matter what fuel I put in it. But it goes down from 9 to 6 if I'm pulling a trailer with a COE sitting on it!
I don't believe there is any magical additive or fuel system that will make a huge difference in fuel economy. The amount of energy in the fuel creates a limit on what could happen.
Diesels get better mileage because there is more energy in the fuel. Running Diesel has a price and most improvements will also have a price. I agree with 4-on-the-floor in that practical engineering concerns have slowed improvements in economy.
If they automakers can't make money selling the cars (like Ford apparently can't these days), they can't spend more money on design and engineering if it won't increase sales.
My mid 80's injected 350 gets about twice the mileage of the 60's carburated 350 I used to drive. Same basic motor, a 350, same type of transmission, and even the same rear gears.
The current version of my current car gets even better from what I read. But the improvements are incremental, and likely will continue that way.
No acetone in my tank please.
