Aero wheels

[brianman]

I can't remember which thread (maybe this one) but multiple people were asserting exactly the opposite.

So, what exactly did you pass on as information? Your vague (and incorrect) memory about the efficiency?

The first quote is information. Even though it was vague (intentionally) and, in your opinion, incorrect (and I disagree) doesn't change that fact.

Now, regarding the previous discussion...

A very large percentage of the energy is lost as heat, and any improvement to aerodynamics won't change that. Aerodynamics is simply a smaller percentage of the energy lost on ICE vehicles than it is on EVs.

At least 3 of us intuitively felt Doug's answer was on the right track, and some tried to restate it in other ways to get the point across. Again, more information -- in this case opinion. Whether you agree or disagree doesn't make an opinion "incorrect". They can be misguided, as can be proven by scientific method.

 

[dadaleus]

Do you have a planned charging station enroute?

Hoping for a super charge, but there is a Tesla store and multiple J1772 sites en route, so yes. But if it's not super charge, aero wheels will shave 20 (or more if just 30amp J1772) minutes of stop time.

 

[ckessel]

This is pretty basic physics. Air resistance doesn't care about the propulsion mechanism. That's not an opinion.

I feel like I'm debating with a "young earther", there's no evidence that would actually change your view. I guess I will, sadly, put you on ignore at last. I suppose we'll all be happier for it.

 

[brianman]

You do seem a little bit emotional at times though.

This is pretty basic physics. Air resistance doesn't care about the propulsion mechanism. That's not an opinion.

I feel like I'm debating with a "young earther", there's no evidence that would actually change your view. I guess I will, sadly, put you on ignore at last. I suppose we'll all be happier for it.

Q.E.D.

I still have no idea what he's upset about -- in the past or present.

 

[Doug_G]

At least 3 of us intuitively felt Doug's answer was on the right track, and some tried to restate it in other ways to get the point across. Again, more information -- in this case opinion. Whether you agree or disagree doesn't make an opinion "incorrect". They can be misguided, as can be proven by scientific method.

To be honest, I was waffling before posting that statement, and again afterwards. I liked ckessel's argument to consider the power plant a black box.

 

[brianman]

For the record, since apparently my opinion matters in some way...

I think both the black-box-power-plant (Doug's current post) AND percentage-impact-of-aerodynamics (Doug's original post) angles of evaluation have some merit.


More on the latter (to perhaps clarify, perhaps not) ...

If you put a 20% efficient ICE against a 30% efficient ICE (with other characteristics such as drag and weight being equal) then I don't expect the impact of drag adjustments to have much impact.

If you put a 90% efficient engine against a 30% efficient engine (w.o.c.s.a.d.a.w.b.e.) then I do expect the impact of drag adjustments to have a more significant impact.

Why? The 30% efficient engine is spending 3x the fuel of the 90% engine, and so the impact is amplified w/r/t fuel consumption.

Of course, this is only if the impact of drag is something non-trivial. If the impact a drag is trivial, then even the amplified values remain round-off error compared to other factors.


Now getting back to this...

Aero wheels have been around forever and would help an ICE efficiency just as much as an EV. If anything, the small efficiency gain would be much more valuable on an ICE due to gas costs.

This adds an additional characterization: "value".

Let's assume for a moment an optimistic ICE assessment: a 5% improvement in aerodynamics is worth twice as much on an ICE as with an EV.

Even with that assumption, leaping to "more valuable" isn't a valid conclusion.


When I reserved my Model S, I immediately focused on the longest range battery available. If price becomes a factor, then drop the Perf, then the Sig...but keep the 85 kWh. Some people won't agree, but that's my mindset.

With every vehicle prior to my Model S, I haven't even been aware of the size of the gas tank until after purchase.

Thus, for me, aerodynamics are far less valuable -- even at twice the payback -- for ICE than for EV.


Edit: I'll take it a step further. Does any consumer vehicle manufacturer offer a larger gas tank as an option on any of their vehicles?

 

[gg_got_a_tesla]

Is noone else watching football?! :biggrin:

 

[brianman]

Is noone else watching football?! :biggrin:

Commercials.

 

[ckessel]

I shouldn't have viewed brian's post. Ah well, I'll only respond to say that if someone is seriously interested in the truth behind the calculations, find someone with a math or physics degree and ask them to explain the actual way it should be calculated.

 

[Lloyd]

Edit: I'll take it a step further. Does any consumer vehicle manufacturer offer a larger gas tank as an option on any of their vehicles?

My guess is that it is not practical to do so. EPA Certification and crash testing, would be the most expensive!! Prior to all the government regulations one could order different tank sizes, or multiple tanks. Now it is left to aftermarket companies to provide extra fuel storage. I have a 38 gallon tank on my chevy pickup.

 

[brianman]

I have a 38 gallon tank on my chevy pickup.

For city driving or for construction, etc. type work?

 

[AnOutsider]

Edit: I'll take it a step further. Does any consumer vehicle manufacturer offer a larger gas tank as an option on any of their vehicles?

Not that I know of. They seem to go for offering higher MPGs these days. You can definitely get it done aftermarket though (and most law enforcement fleet vehicles have this done).

 

[Lloyd]

Hunting trips and distance driving. I take several trips a year where I am offroad for a week or more at a time, and travel to Montana or Wyoming. Gives me 600 miles of range with reserve!

 

[brianman]

Not that I know of. They seem to go for offering higher MPGs these days. You can definitely get it done aftermarket though (and most law enforcement fleet vehicles have this done).

Good to know. Aftermarket is a bit of a different beast though. I'm sure you can find aftermarket that will remove weight, change body shape, replace the engine, etc.

Contrast that to Model S (and perhaps other EVs, I haven't been looking) where size of battery is one of the primary configuration choices.

 

[AnOutsider]

Contrast that to Model S (and perhaps other EVs, I haven't been looking) where size of battery is one of the primary configuration choices.

Well, if you want to look at it that way, then one could consider the different engine (MPG) choices the direct comparison to that. Major differences though is that the financial hit is usually less up front (which consumers seem to prefer) and that in an EV, the perception is that your range is the end of the line -- whereas in an ICE, that's just the point at which you need to start hunting for a station.

 

[brianman]

in an EV, the perception is that your range is the end of the line -- whereas in an ICE, that's just the point at which you need to start hunting for a station.

Indeed. Hence the "value of longer range on same fuel" difference between EV and ICE.

It's both the abundance of fuel stations *and* the refill time that makes EV's (currently) see more value out of aerodynamics improvements.

 

[neroden]

OK, here's a question:

How the heck do you change a tire with aero wheels? How do you get at the lug nuts?

 

[William13]

I ass/u/me that the aero wheels are aluminum wheels(weight considerations) with hubcaps that are flat or have golf ball type indentations. You would pop the "hubcap" off and then see the wheel with lug nuts.

 

[neroden]

I ass/u/me that the aero wheels are aluminum wheels(weight considerations) with hubcaps that are flat or have golf ball type indentations. You would pop the "hubcap" off and then see the wheel with lug nuts.

I have been having trouble spotting the hubcap edges on the photos of aero wheels, but that makes sense.

 

[brianman]

I ass/u/me that the aero wheels are aluminum wheels(weight considerations) with hubcaps that are flat or have golf ball type indentations. You would pop the "hubcap" off and then see the wheel with lug nuts.

I wonder how much it will cost to replace these "hubcaps" when they get stolen. :|