XtremeRevolution said:A. Tire pressure/Tires.
…A lower tire pressure will soften the ride and provide better dry traction, but will cause more heat due to rolling resistance and reduce fuel economy. Too low of a tire pressure can result in catastrophic failure. A higher tire pressure will stiffen the ride and may compromise dry traction, but will improve fuel economy as much as 3-4mpg.
As your subsequent post clarified, increasing tire pressure has little/no effect on braking distances on various surfaces. What is not mentioned, however, is loss of traction on rough surfaces. Running tires at significantly increased pressures from the manufacturer recommendations increases the amount of rebound a tire has when impacting a bump in the road, which reduces the suspension’s ability to keep the tire in contact with the road not only during braking, but cornering and accelerating as well. People who regularly drive on rough pavement or on gravel/dirt roads may wish to stay closer to the recommended pressures than those who typically drive on better surfaces.
My ’12 Eco recommends 35 psi on all four tires. My personal preference has been to leave the rears set to 35 and increase the fronts to 38 psi since the car carries more weight on the front tires, evening things out a little. I tried increasing all tires to 44 psi, but the increased ride harshness was not worth it (for me on my local roads, anyway).
Another thing to note about tire pressures: the rolling resistance of a tire will increase exponentially as the inflation pressure drops. What this means is, rolling resistance will decrease less and less the more you inflate the tire. Specifically, the difference in rolling resistance will be much greater going from 25-30 psi than it will going from 35-40 psi. The main take-away point here is that making sure your tires are not under-inflated is FAR more important than over inflating them. I personally look at over inflation by a few psi as a way of making sure tires are always at least at the recommended pressures. Setting them a little high gives some room for deflation between top-ups.
XtremeRevolution said:A. Turn off your heater.
Generally good advice for the reasons you state, but once it gets below freezing you have to get the windshield warmed up above the dewpoint to keep it defrosted.
My tip here is to use the heater on the full windshield defrost setting, but only set the fan to low speed. The more air you pump through the heater core the more heat you pull from the coolant and the longer your engine will take to warm up.
Also note that the AC will not engage when temps are close to or below freezing. Normally the AC comes on when the full windshield defrost setting is chosen on the HVAC control, but in colder temps this is not an issue.
RIGHT ON THE MONEY!XtremeRevolution said:B. Watch your RPMs… …I shift into 2nd gear as soon as possible, hit 2000RPM in 2nd, then keep RPMs below 1500 from 3rd through 6th gear. I'm in 5th gear at 35mph and 6th gear at 40mph, cruising at 1100RPM...
XtremeRevolution said:D. Turn cruise control off. Unless the road is completely flat.
While I agree with most of what you said RE cruise control use, my general advice is to use cruse control as often as possible, unless the terrain is hilly. Kinda the same thing you said, just reversed a bit.
My reasoning for this; it’s almost impossible to manually keep your speed constant, and doing so requires a large percentage of your available concentration. Unless heavy traffic dictates otherwise, using cruise to regulate your speed will generally reduce throttle angle variations (as you constantly speed up and slow down keeping your target speed), keep you from exceeding your desired speed (which uses more fuel), and frees up your mind so you can concentrate on the traffic around you and changing conditions ahead (which saves more fuel than the cruise may waste regulating your speed).
If you’re driving in hilly conditions then, absolutely, do not bother with cruise control. As you stated, anticipating an incline by gently speeding up before it and gradually losing speed while climbing is much more efficient.
This is both true AND false, and unfortunately for those of you in the US it is not apparent why. Let me explain…XtremeRevolution said:F. Have a Manual Transmission? Keep the transmission in gear while coasting to a stop. So long as you're above idle, the engine will actually shut off the fuel injectors and allow the transmission to turn the motor over, using zero fuel. While automatics will also do this, you have greater control with the manual. Don't put it in neutral when coming to a stop, leave it in gear until your RPM drops low enough to need to shift out of a gear.
First of all, the Cruze DOES indeed shut off the fuel injectors when coasting… AS LONG AS THE ENGINE IS SPINNING FASTER THAN 1500 RPM WHEN YOU LET OFF THE ACCELERATOR. If the engine is spinning less than 1500 RPM when you back off the accelerator it will keep fueling the engine, which uses more fuel than coasting in neutral with the engine idling. When coasting with the injectors off, the car will turn the injectors back on when RPM drops to 1100 RPM.
How do I know this? I AM CANADIAN. J
Seriously, the fuel economy (consumption in Canada, EH) readout on the DIC is the culprit. When displaying in US units, the highest number the display will read is 99 MPG. This is a LIE when the injectors are turned off during coasting, as the car is effectively getting INFINITE MPG, not 99. Unfortunately, there is no distinguishing between 99 MPG and infinite MPG in the DIC, so you can’t actually see when the injectors turn off and back on again.
When displaying Metric units on the DIC your fuel consumption is displayed in L/100km (idiotic in my opinion, but that’s the way the “powers that be” have made it). The advantage here is that the display WILL read 0.0 L/100km when the injectors shut off, and then resume reporting consumption when they turn back on again. Finally… an advantage to living North of the border! J
What this means is, if you want to save the most fuel possible you need to either:
A: Make sure you’re revving at least 1500 RPM when you let off the gas, or
B: Downshift into a lower gear when coasting to get above 1500 RPM
For hyper-milers that keep their Eco MT’s revving as low as possible, this is good to know. For you US based Eco MT hyper-milers, now you know.
This is a GREAT post, Andrei! Some of the more experienced maxi-milers may debate a few of the finer points and how they apply to different people’s driving scenarios, but as a general read for the average (and un-mileage-educated) driver, this is PURE GOLD. I’m glad to see this is a sticky and I only wish EVERY driver was forced to read and pass a test on this information every time they renew their driver’s licence.
One point of my own I will add to this thread is regarding the most efficient cruising speed. This comes to mind mainly after speaking with a friend of mine who drives a Honda Hybrid and is INTENSELY interested in all things green (he has $30k worth of solar panels on his roof, for example).
This friend of mine made a casual statement that the most efficient speed to drive is 80 km/h (50 MPH). It seems this information is being spread about, regardless of which car you drive.
Generally speaking, the most efficient speed you can drive is:
THE SLOWEST SPEED YOUR CAR CAN COMFORTABLY GO WHILE IN ITS HIGHEST GEAR.
Comfortably in this case meaning able to maintain its speed considering any elevation changes or increased drag due to wind, and usually involves an engine speed around 1000 RPM or slightly above. For a Cruze Eco MT, that speed is going to be between 35-40 MPH.
If anyone wants to try verify this, go to a long flat/level stretch of road with no traffic on a calm day with no wind, and driving back and forth across the same stretch of that road record two-way average fuel economy readings at different speeds. If you want to make it really interesting, try it in different gears also. This will quickly demonstrate why “overdrive” transmissions are popular/necessary, and why the Cruze Eco has THREE overdrive gears.