Yes, but the more fuel you purchase at one time (ie, wait till the tank is pretty empty) this margin of error gets smaller & smaller.
The largest margin of error is not the gas pumps decimal place, but how much you fill your tank. I try to top every tank off the same, but I know of no exact method of doing so. I do try to use the same pump, but this only helps a little. But if you think about 50 fill ups, this +- .02gal per fill will obviously balance out, as you only take fuel out one way (hopefully) and your tank doesn't change size.
Back to the WAI (i haven't been online for a wile, so i'm jumping back several posts here)
WAI shouldn't effect burn ratio at all, if you what to lean it out you should bust you O2 sensor reading by 30mV or so (not recommended if you don't have a EGR)
The intake temp matters very little to the computer, just a way of making sure everything is okay.
The benefits as i see them:
1)As stated several times, less air mass needs less fuel to burn in the way that will make your O2 sensor happy.
2)Theoretically (probably true, but may not give mensurable improvements) Hot air will hold fuel vapors better. Thereby your injectors work a little better. This is even more a factor when you think about injected fuel boiling before combustion, which must happen to some degree with a warm block, and high vacume.
Blocking your intake is doing exactly the same thing is closing the throttle. The only difference is that it's doing it further from the engine.
The throttle is already very good at its job of throttling.
What's more effective in many cars is to shift lower and open the throttle more, so the engine isn't wasting energy on the extra work required to get air past the closed throttle. You produce the same amount of work, accelerate the same, but you use a little less gas because you waste a little less energy.
I'm really leaning toward the warm air intake not really doing anything except cutting power to your engine. Just like restricting the air intake inlet will cut power... just like not opening the throttle as much. So really, instead of spending any money on modifications lets all just not accelerate as quickly.
If you want to make your engine truly more efficient then you should reduce rotating intertia within your drivetrain. Lightweight flywheel, gun drilled camshaft, smaller cluth, lightweight pistons etc. All of that is way too expensive to even consider if your goal is to save money on fuel cost.
Reducing friction with exotic ceramic coatins and what not would also help a bunch, but once again it's not practical. The factory engineers already optimized the desgin of aerodynamics with regaurds to functionality and performance, so any gains there are minimal. (Just put tape on your grille for long drives).
Really the only practical thing to do is not drive as much and drive slower when you do drive. Hypermiling is tough on equipment. Like not letting your car warm up on those cold winter mornings is AWFUL for your engine. Maybe you'll save a few bucks but if your engine fails then all that money you've saved goes into repair.
I agree that hypermiling can be hard on the vehicle. I suspect that my transmission problems in my 98 K1500 were due to me hypermiling in a 10 year old vehicle with over 150,000 miles. My Torque Converter started slipping, and that was after a few months of inducing DFCO by downshifting, shifting into Neural at lights, etc. I am now not as extreme in my efforts, balancing economy with wear & tear on the vehicle. The new torque converter + flush & fill the tranny with synthetic ATF cost me about $1,000. I still manage to do a percent or two over EPA estimates with most of my driving being short trip city.