[GJETSON]

locked into 65 mph the whole way (and I tend to feather the throttle on downhills to keep the power meter around +1-3 kW to avoid some of the regen losses by going a few mph over the cruise control setting).

What? That is not how this works. What you are doing is increasing you average speed slightly...to prevent regaining energy.

 

[GJETSON]

He's trading decreased regen for increased momentum, assuming the downhill eventually becomes uphill again.

Which is the same thing I said, but avoiding realizing he is using more energy to go from point A to point B. He saved some number of seconds going downhill (increased the overall average speed by some amount) by expending more (not regaining any) energy. Why is that so hard to understand?

 

[GJETSON]

Let me try again. He has the CC set to 65 mph. At the crest of the hill he is going 65 mph. As he goes downhill, he is increasing speed without regaining any energy until, if he does it exactly right, he lets the car go back to 65 mph without overshooting. His average speed has now gone up slightly. He still has to get to B at 65 mph.

Your assumption is that he will coast some distance up the other side, or along the flat, further than he would have traveled, given the same energy expenditure at 65 in CC. That high speed coast was not at 100% efficiency either, and probably no better then regen in that regard.

My suspicion is that there is no more energy, and possibly less, in the battery than there would have been, had he let it regen at 65 mph down the hill.

 

[GJETSON]

Aerodynamic drag is easy to calculate, as is the approximate efficiency of regen. I'm pretty sure the more time spent coasting (even with the extra aerodynamic drag on modest grades) still conserves more energy that the guaranteed efficiency losses in regen. Obviously long, continuous downhills and those with very steep grades are a totally different story. The rolling hills in Northern Kentucky usually add about 2-5 mph if I try to maximize coast time on all my downhills for my daily commute.

So the few watt hours you might theoretically save looking at the kW gauge on the right side of the DIC, instead of looking out the windshield, is worth the increased chance of an accident?

 

[GJETSON]

Physics pisses me off, I get the wheel covers, but adding stuff to the back shouldn't do anything. Why fluid dynamics, why?!

The front is less important than the rear. Any bulbous front is pretty good at punching a hole in the air. Getting the air to exit without rolling around behind the car is more important.

 

[GJETSON]

Having the air "stick" to the back end causes drag. Adding parts that cause the airflow to make a clean break from the back can reduce drag. It's the functional reason for the spoiler at the top of the rear window. That civic is like a full body spoiler.

A design that causes the airflow to come back together before that clean break is even better...but pretty bad from a packaging standpoint.

 

[GJETSON]

Don’t know if these wheel filler plates would help but I found them on this website if you have access to a 3 d printer and want to try.

Sure would. GM had clear ones, just like that, on the Bolt concept car in 2015.

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