Erik, cc (plus) can actually do an okay p&g on my slushbox. Nudge to neutral to glide (that auto disengages the cc), nudge back to gear and tap resume to pulse (the acceleration on the pulse is actually quite optimal). Above lockup speed however, I can't detect any improvement using P&G.
It was funny, I'm in our stick Accord and sensed no load on the tranny while driving at a city speed, so I nudged it into neutral to glide. The cruise was still engaged and I wasn't thinking (no clutch or brake was engaged to disengage the cruise). Luckily it wound up quite slow and the stereo wasn't too loud so that I caught the engine as it not much after it hit 5K...
Personally, I like to draft. My commute is mostly highway, at rush hour. But, oddly enough, finding a good draft can be difficult: The truck going slow in the right lane is getting off at the next exit. The out-of-town semi's go slow, but they don't know where they are going, and keep changing lanes. The local semi's know which lane to be in, but they are going 70mph. And the construction trucks are going slow, but they drop gravel and mud at every bump. I only find a good draft about once per week.
Fortunately, rush hour gives me a good corridor effect. I find that i get the same mileage going 65 in the middle lane, flowing with the traffic, as I do going 60mph in the right lane, punching my own hole in the air. Hey, we're all drafting at rush hour . At non rush-hour, though, you'll find me going slow in the right lane.
As to safety, I feel much safer following a semi at one trailer-length, than I think those folks in the left lane are: going 70mph, one car-length apart.
The scenario where everyone is driving faster benefits you regardless, every time a vehicle passes it helps pull you along a little bit.
Be careful doing this, but perhaps a minor adjustment in your lane position might enhance the effect, which is to say I think the closer you get to the car passing the better, but I wouldn't get no closer than say the center of your lane.
I think if you were riding near center it would be better for mpg than ridge riding when cars are passing, but I'm not sure, it may not benefit at all too.
The rest of this refers to other types of drafting:
The inherent problem with long-term drafting is that the tailgater has to constantly re-adjust their speed to keep from hitting my trailer, not to mention safety factors and my own dislike against the practice, the numerous speed adjustments will waste at least as much fuel as the drafting saves, so it rules this out.
The minimum following distance is 2 seconds, now I am 100% certain that by the time drivers enforce this there is no way they can draft at the same time.
I don't want to scare anyone nor is this a dare, but don't ride bumper
So I think this only applies for a slow down glide, say for instance you're coming in faster than I am driving so you decide to stay off ICE until you've regained a NON tailgating distance, so you coast in behind me to benefit from the tailwind until such time that you have to re-enable ICE. In this scenario you could stand to gain some free distance from the tactic, and this is likely the only tailgating most drivers would tolerate, so long the drafters do fall back in relatively short order.
A FE gauge should be standard equipment in every vehicle.
It's rare that I can find a vehicle to draft.
But sometimes I do, and I go with it till it doesn't work any more.
I like buses and other vehicles where their back end goes lower to the ground than the typical 18-wheeler. When I can find such going a decent speed, of course. I figure the drafting effect is better when the lead vehicle's body reaches close to the ground, like mine does.
Currently getting +/- 50 mpg in fall weather. EPA is 31/39 so not too shabby. WAI, fuel cutoff switch, full belly pan, smooth wheel covers.
I just watched the Mythbusters on drafting and gas saving - they keep saying throughout the entire show that it is dangerous (but not why it is) and they got some significant fuel savings until they got within 2 feet of the tailer and then it got less savings. I think the wind tunnel test of the model car and box was very interesting when they actually measured the force change on the model car. The real world test was with a Dodge Charger wagon (baseline 32mpg at 55mph!) and a new low drag Freightliner truck. One reason for the poor mileage at 2 feet was from the constant gas pedal movement to maintain the 2 foot distance. They did see savings as far back as 7 car lengths 21% in the wind tunnel test at 55mph so you can realize even more savings at higher speed.
While drafting a truck from a safe distance may give minimal results, the space between you and the truck ahead can provide more room to pulse and glide between 55 and 65mph. A lot of trucks either have speed limiting devices or drive at 60mph by choice to save fuel. Watching the traffic coming from behind, gliding when distant and closing the gap between you and the truck when traffic is coming closer. This keeps most from diving in front of you just to have to pass the truck seconds later. Also the traffic coming from behind will see the truck easier than your small car and will change lanes to pass earlier and not try to force you to go faster by tailgating ( as it's not going to work on the truck anyway). This also works with the big truck behind you as the other traffic has already changed lanes and wouldn't bother getting back into a limited space behind a slower car( most people just want to remain in one lane as long as they can).
Truckers basically don't like cars behind them, in front of them, beside them or anywhere else. They believe the roads were made to haul freight only and everyone else is trespassing.
truck drivers do not like other vehicles around them because the Smith System(truck driver training) dictates it. WHEN POSSIBLE, we are taught to keep a cushion(open space) around our large mass in case of emergency braking/manuevering. "leave yourself an out" is the short version.
at high speeds this is vitale, obviously. at low speeds it is not always possible and difficult, but not as imperative.
if passenger vehicle drivers REALLY knew how difficult it is to stop/manuever such a large vehicle, maybe there would be more courtesy extended to us.
i tell people there is no such thing as a minor collision involving a truck.
interestingly enough, my company now makes, ANY employee that drives ANY vehicle at work, take the smith system. imagine making this mandatory for all drivers(with periodic retesting)...could prevent many collisions and/or traffic jams.