Yep, its the law you have to drive a rental car like an idiot... and 3 neutral drops are required by law.I think there is a law against applying "fuel saving" procedures to a rental car! No?
Engine braking never changed. Engine braking in my truck is about the transmission programming (automatic). The computer will hold the torque convertor in lockup until about 15 mph where it releases the convertor lockup (it's quite noticeable). As long as the convertor is locked upon deceleration, engine braking is quite effective.How does your engine-braking feel now? Similar or is it gone now?
That right there is the single most important factor, swamping all others. It also means higher situational awareness and of your momentum. This makes you a safer driver, seeing things sooner and avoiding collisions or other hazardous conditions. It will also make your brakes last longer.Improving fuel economy ... My definition of a good driver is one who rarely uses the brakes. This is done by constantly looking as far ahead as you can, in some cases a mile or so. In areas where you know the pattern of red lights and traffic patterns you can improve on fuel economy by 5 or 10 MPG assuming all else is correct with your vehicle. You anticipate what will happen in front of you. You will maybe slow down a little as you approach a traffic light but rarely stop. Take turns a little faster. Coast as much as possible.
I too use a Scan Gauge. It shows 9999 MPG on my Ford Escort from about any speed until it's down to a specific RPM around 1100 RPM if I recall correctly.Everyone says that, but do you have any evidence? Other people saying it somewhere else online? Even the engineering explained guy assumed this is true without actually testing his cars. My scangauge reads what the ECU is doing in real time through the OBD port, and in my cars true fuel cut off is only at rpms way above what you use in top gear. At 60 mph rolling down a hill in top gear every car I've owned uses about 30% more gas coasting in gear than idling in neutral, plus you are using engine braking to loose speed. It seems crazy that's what they do for emissions, but that's what they do.
I believe SUV's and trucks have slacker emissions standards and they do cut fuel completely more often, I haven't tried the scanguage in the Outback yet, but our 2003 Tracker would completely cut fuel when coasting down to near idle speed. I don't recall if it would do that before the engine was at normal temps though.
What year is that car? My 1995 Neon automatic wouldn't cut fuel except at high high rpms. I guess it sure depends on the vehicle.I too use a Scan Gauge. It shows 9999 MPG on my Ford Escort from about any speed until it's down to a specific RPM around 1100 RPM if I recall correctly.
Good analysis but need to figure in lower pumping loses with the more open throttle, too. Can be as much as 20%. Your analysis treats aerodynamics as the only consideration in fuel economy. Just one of several.That right there is the single most important factor, swamping all others. It also means higher situational awareness and of your momentum. This makes you a safer driver, seeing things sooner and avoiding collisions or other hazardous conditions. It will also make your brakes last longer.
The other one is driving slower on the freeway. Fuel consumption is roughly proportional to power output, and power increases with the cube of speed. That is, twice the speed requires 8 times the power, and 10% faster requires 1.1^3 = 33% more power. Of course, at higher speed you travel further in the same time, so fuel economy relates to the square (not the cube) of speed.
For an simplified example: suppose you go twice as fast. Air resistance (drag) is proportional to the square of speed, so you have 4 times the drag. That means 4 times as much thrust (or force) is required. Over the same distance, 4 times the force is 4 times the work. But you travel that distance in half the time. Power is work / time, so this means 8 times the power. That means you burn fuel at 8 times the rate. But you did this for half the time, so you've burned 4 times as much fuel to travel the same distance in half the time.
Now 75 mph is about 15% faster than 65 mph, so you'd burn 1.15^2 = 32% more fuel traveling the same distance. Or, slowing down: 65 is 13% slower than 75, so you'd burn 0.87^2 = 76% of the fuel going the same distance. That's about 1/.76 = 31% better fuel economy.
All else equal of course, that's basic theory and real world figures will vary.
A while ago I tried to drive the limit in my car; end result was the fabled 10% bump in mpg. That proven I went back, 10-20% decrease in driving time was fine by me in losing 10% in fuel economy. Considering I typically spend 2 hours a day in the car, it was measurable.
Why should vehicle size relate to concern about fuel economy?I love you guys with three ton vehicle worrying about fuel economy.
True, which relates to my "all else equal" comment at the end. All else is never truly equal in the real world.Good analysis but need to figure in lower pumping loses with the more open throttle, too. Can be as much as 20%. Your analysis treats aerodynamics as the only consideration in fuel economy. Just one of several.
Conditions and safety permitting, rpm @45-50% of red line is the most efficient engine speed to run at (or torque peak).True, which relates to my "all else equal" comment at the end. All else is never truly equal in the real world.
However, if in top gear, the engine revs are so low at 60 mph that the engine would actually run more efficiently at 70 mph, that alone isn't sufficient to get better MPG at 70 mph. The difference in efficiency would have to be so great as to overcome the higher drag. That's unlikely, as drag increases with the square of speed. What is more likely is MPG still drops at 70, but the drop is less than predicted, as it's partially offset by slightly improved efficiency.
I aim for 5 mph over the limit and go no higher than 9 mph except in the rare occasion I'm in a cluster going faster.I tend to think people that drive under the limit or way over it are complete morons that are not achieving anything.