Originally Posted by COchief
Thanks for taking the time to make an intelligent reply.
My X doesn't idle at 3k, but it sure as shit will hold at least that when I am coming down the Mtn at a 6-8% grade (I told you I live in CO for a reason).
Are you really going to argue the point that if the same two cars are driving at 3500 rpm and one hits neutral, and the other slowly winds down that there will be no benefit of one engine being at 800 rpm vs 3500-3000-2500- for a period of time? The savings may be fairly minimal and the new trannys may help with this, but no way does that not burn more fuel. It may be semantics at this point, but even that point of releasing the gas vs an almost immediate drop to idle on auto vs manual will create a minimal savings. Remember you are arguing that if I have an s2000 at 9000 rpms and engine brake to a complete stop vs neutral it will be the exact same. Bullshit, you seem to be an intelligent individual, surely you can admit that even though the savings might be minute, a manual is definitely more efficient in this scenario.
I twice said pads were a hundred bucks, a hundred is pretty much standard for any shop to swap the front pads. You're really grasping with that. I have owned several performance vehicles that have been taken to the race track (a real road course, not a parking lot SCCA or circle track). I don't need brake repairs explained to me thank you very much.
I'm saying that you're looking at 1 of 2 possibilities here.
1) The car isn't going to stay at 3500 rpm - it's going to simply idle down. Unless you're referring to the second it will take for the computer to realize that you're not accelerating (and if you were in overdrive, it shouldn't even take that long), there's no practical difference there. Take your foot off the pedal and your ECU will get to work keeping your mileage up - it's a cheap and easy way for Ford, etc... to improve fuel economy without drastically changing the motor design. Now, the other possibility is what I think you're referring two and thats when you're coasting down the hill (foot not on the gas) and your RPMs have come up to keep you from going 100 mph - in other words, 'involuntary' engine breaking.
2) Again, engine breaking does not have any impact on fuel economy. You may be right, on your steeper grades in Colorado your manual might be pushing 3500 going down the hill. But that's not a true 3500 - it's an idle speed that your transmission is running up to 3500. You're not using any more fuel there than you would if you stepped on the clutch. The fuel isn't what has you at 3500 - the wheels are.
The only difference in MPG would come from the fact that by engine breaking, you're reducing the distance you travel. If it takes you 5 seconds to stop, you will have used the exact same amount of fuel over those 5 seconds as you would have if you'd have just stepped on the clutch - but if you just step on the clutch you'll still be traveling, so your MPG goes up. Presuming, however, that you're stopping for a reason, you're just going to use your brakes to stop at the same point there's no actual travel gain.