As you read the previous posts on this thread, you can see that I abruptly stopped the discussion before addressing the key i-MiEV range-robbing element: aerodynamic drag at speed.
The solution is elementary: have some large vehicle push the air aside and then follow it. The range-increasing results are dramatic! This graph http://myimiev.com/forum/viewtopic.php?p=17565#p17565
needs no explanation - imagine traveling at 60 mph while only facing an effective headwind of, say, 30 mph: from the graph, instead of a range of 50 miles at 60mph we now get a range of 100 miles!
No, I'm not advocation NASCAR-style drafting, but a significant benefit can be derived from following large vehicles, yet at a distance that allows for taking evasive action in emergencies.
As some of you might recall, last June while traveling on Interstate 5 in my Gen1 Honda Insight I was hit from behind by a drunk driver. Before the accident I had been safely following a huge truck for a couple of hundred miles but, unfortunately, the truck had just turned off the highway and I was left nakedly exposed continuing down the highway at 60mph (the speed limit for cars on this very long and straight Interstate is 70mph), of course in the right lane. Within a couple of miles I got whapped as this drunk veered from the left lane into mine while traveling at what I estimate to be >100mph. The string of cars in the left lane was passing me going around 70mph and this driver came upon them quickly and suddenly veered into the right lane not seeing my small car there. I'm happy to be alive, but this incident got me thinking about the whole issue of efficient driving, visibility, and safety.
Following trucks has the major disadvantage
of one not being able to see the road ahead, which means that road debris can unexpectedly and unavoidably suddenly appear from under the truck. Sadly in recent years, this is also a peril for all small car drivers as SUVs and pickup trucks have proliferated the landscape. This is also the major hazard motorcyclists face on a daily basis.
The other traditional concern of following trucks too closely simply doesn't apply: barring a sudden-stop accident by the truck ahead and given reasonable responsiveness by the car driver, in an emergency the car will stop much faster than a truck.
In California, multi-axle trucks have a speed limit of 55mph, which means that they usually travel at 58-62mph, a speed that is just fine for covering longer Interstate distances in our i-MiEV. Based on my own recent experience described above, the major advantage
of driving at 60mph and following a truck is that the truck offers a visual barrier to anyone coming up quickly from behind.
When following trucks or other large vehicles, each of us must decide for ourselves what the comfortable and safe distance is for that particular scenario. For example, I do try to avoid situations whereby I'm sandwiched between trucks, and instead prefer just tagging along behind a solitary big rig.
After three years of driving my i-MiEV, I must say that I've rarely employed this range-maximizing technique. Almost all of my driving entails highway trip distances of under 60 miles, which the i-MiEV does comfortably without resorting to extreme hypermiling. It is only the occasional extended trip between sparse recharging opportunities which benefits from having this ace up my sleeve, if needed.