New here, and while the list is already long there's a lot still missing...
The idea behind the "racing line" is to find the lowest time through a corner (or set of corners), not necessarily the fastest speed in the corner or shortest distance, generally given that you're driving at the limit of adhesion (which you typically won't find if you're hypermiling).
Learn to drive so that you don't have to slow down so much in a corner - carry your speed through the corner, and perhaps in a higher gear, too, whether in the dry, the rain, or in snow.
Not all tires with the same nominal size actually have the same diameter; a 215/50-17 Falken 512 is a lot smaller than the same size Michelin HX MXM4. The difference will affect gearing, and acceleration, handling, cornering grip, etc.
Different makes and brands of the same size tire can have different weights; tires of the above noted size typically range from 23lbs to 28lbs.
Reducing the weight of wheel and tire can have a dramatic effect on handling and acceleration, and fuel economy. Reducing the unsprung weight at each corner by, say 5 lbs, will reduce the total weight of a 3,000lb car by 20lbs - so what! There's the obvious effect on the suspension, which can react faster to changes (bumps, etc), for improved handling (so you can drive faster through corners). The reduced rotational mass means that it is easier for your engine to accelerate the drive wheels - think increased area under a thurst-at-the-road cuvre: the net effect is that your car will have more torque available AT EVERY ENGINE SPEED for acceleration, when driving up a hill, or just driving a long (because there will be less load on the drivetrain).
Failing to signal a turn might hurt another driver's hypermiling. Consider if you're waiting for an approaching car before turning into traffic - so you're idling - and just before that car gets to you it turns so that it is no longer in your intended path. In some situations, if that driver had signaled their turn, you might not have needed to wait.
It seems that many people do not understand that, if they accelerate vey slowly, they may be maximizing their time in fuel inefficient 1st and 2nd gear. AND, they may selfishly be forcing the drivers behind them to do the same.
Hypermilers using a steady-throttle on rural 50mph roads may selfishly be causing cars behind them to become less fuel efficient. My 4-cyl Acura has a slippery 0.27 drag coefficient, and it moves just fine, but it's aggressive 6-speed manual transmission masks its general torque deficiency. So, when traveling behind a hypermiler who slows from say, 50mph to 45mph going up that hypothetical hill, I now downshift from 6th gear to 5th gear: that hypermiler may be helping them justify buying a fuel inefficient car, but they're NOT helping the planet.
I didn't see any comments about skipping gears, when accelerating. In the city, I used to go 1st, 2nd, 5th, unless I went 1st, 2nd, 6th. I have read on in an Acura forum that Acura does not approve of this, and suggests that drivers [seemingly pointlessly] run up through all the gears, even once you're hit cruising speed - Acura's interest is transmission wear/gear alignment or something like that.
I don’t skip as many gears as I used to because I changed the overall gearing of my car by increasing the size of my tires from 215/50-17 to 225/50-17. I did not do this to save fuel, and although the engine now runs slower in every gear, at whatever speed I'm going, the effect on gearing makes it harder for the engine to turn the car's driving wheels. The point is that unless your car has a lot of surplus torque, changing your car's gearing by increasing the diameter of your car's tires might not improve fuel economy, or it may depend on how you drive. [For those interested, I "made my car accelerate slower" so that I could use 3rd gear again, I wanted more cornering grip (but I now have slower "turn-in", and I'm paranoid about Ontario's 50-Over Stunt Driving Laws - and before you laugh recognize that people here have had their cars impounded and licenses suspended for spinning their tires pulling away from stop sign in the snow even though they had snow tires on their car!]
I didn't see any references to "lowering springs" which can make your car handle and brake better, and improve overall aerodynamics, giving either reduced fuel consumption or improved acceleration - or both. Ontario's approach is that making these type of improvements means you must be a "street racer" and warrant being pulled over and harassed. Anyhow, lowering you truck, minivan, or SUV (or car) with shorter, generally stiffer, springs - and throw in some new shock absorbers, too, while you're there - might save lives, make driving trips take less time, and save fuel.
Engine/intake/exhaust modifications don't seem to be included in this section, but making an engine more efficient might mean that you can drive in a higher gear, at a given speed. Generally, however, improving engine efficiency means using more air, which is burned with more fuel, so that may sound like a no, but if it means that you can use a car with a modified 4-cyl engine instead of the came car with it's optional V6 to haul the family around with, then, maybe....
In the past week, I've been forced out of my lane when a [presumably] hypermiler refused to safely and reasonably accelerate onto a highway. Again, they may think their saving fuel, by maximizing their time in a lower gear at 40mph in a 60mph area, but the planet isn't any better off.
Modern engines mix and burn air and fuel according to their maps, but when it's cold outside and the air is dense with higher levels of oxygen your car will burn more fuel. So while the air may be harder to move through, your car will be more powerful.
Some tires are better than others, and some should be illegal. A tire that prematurely loses its wet-weather grip (I'm talking about the continuation of the vulcanization process when tires heat and cool when driven, upon rather than from treadwear) can leave you uselessly - and dangerously - spinning your tires to get going. Just a thought, but has anyone looked at the wet-weather ratings of the Goodyear Integrity - a tire recently popular on Dodge minivans and Toyota Corollas, plus millions of other cars - on
Tire Rack - Your performance experts for tires and wheels
Anyway, I've got to go, but I'll be back.