The 1963 Cadillac was stated as having 51.2 Taxable Horsepower.
What Is It?
Is it still being used in the USA?

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Another ruse by some states to get tax dollars from car owners. East Coast states like NY and NJ, if I remember correctly.  

I do not know how the number was calculated, but if you divide 325 (hp) by 51.2 that = 6.347.  Was that the common denominator used for all cars?   

It was another method for taxing automobiles, and per some quick research seemed to be more prominent outside the US, but was used by some states, and according to Wikipedia is still in use in Missouri.
The Taxable horsepower rating is derived from a RAC formula as follow:

{\displaystyle {\frac {D\times D\times n}{2.5}}}


D is the diameter (or bore) of the cylinder in inches,
n is number of cylinders

Plugging in for the 63 390 I get:
(4 X 4 X 8)/2.5 = 51.2.

As we all know, just because something is on Wikipedia, does not make it fact, but did some quick checking on other sites and the seems to be the formula. As far as Missouri still using this, that probably needs to be verified.

You can see the full Wiki entry by Clicking Here.

With that,
Van, Have a Big Cigar!

Thanks for the "flaming actor" prize, Jason!

I wonder what those same states did/do with a rotary-engined car?  

That’s the cover of Pink Floyd’s “Wish You Were Here” album which has their song Have a Cigar. Just oddball humor.

 I  will have to find it but remember reading how some states are grappling on how to tax the electrics, since it will increasingly become another revenue source.

Here is a slice of one story I was reading:

“A few states have explored a per-kWh fee for EV drivers. Since most charging occurs at home, a per-kWh fee on EV charging could require a separate meter for determining which electricity consumption was for the EV. This could be avoided through submetering, relying on the meters embedded in EVSE or the vehicles, but the process of implementing submetering and separating out the EV electricity usage from the household usage does carry a cost.”

CA (where I live) is pushing hard for an additional "per mile" driving tax for every vehicle, not just EVs.  

Even though it's the rapid sale of EVs that caught the state's income collectors' beady eyes in the first place.

As more and more states mandate a "No new ICE vehicles to be sold in this state" edict in the near future, they'll be extending their tentacles even further into our wallets.  

I dig Pink Floyd too, and still have my original Dark Side of the Moon double-album. But, I admit I probably haven't looked at it for 35 years. 



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