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Taylor95 10-26-2020 05:47 PM

Cd or weight?
 
Imagine that you are buying a new vehicle to modify for fuel economy. You plan on using this vehicle for 50/50 city and highway driving. You have narrowed your choices down to two vehicles which are virtually identical except for the following:

Vehicle A has a 10.0 Cd advantage over Vehicle B.

Vehicle B weighs 1000 lbs less than Vehicle A.

Which one would you choose, and why?

CigaR007 10-26-2020 06:28 PM

I would be inclined to say that it is easier to reduce the Cd.

1000 lbs is a lot of added weight and you would be making sacrifices to shed a portion of it.

jakobnev 10-26-2020 06:44 PM

This man has a dog and a mother in law that don't like each other!
How do I know?
Elementary my dear Watson, the dog likes to have it's head out of the window, and the mother in law is a bit on the heavy side.
And he has to choose only one to bring on the vacation trip!

freebeard 10-26-2020 07:27 PM

Quote:

Vehicle A has a 10 point Cd advantage over Vehicle B.

Vehicle B weighs 1000 lbs less than Vehicle A.
IIRC 10 points is 0.10 Cd.

It's all relative. Beginning Cds and weights are...?

Taylor95 10-26-2020 08:28 PM

Quote:

Originally Posted by freebeard (Post 634728)
IIRC 10 points is 0.10 Cd.

It's all relative. Beginning Cds and weights are...?

The question is purely hypothetical so actual values do not matter.

However, Vehicle A could have a Cd of 0.25 and weight in at 4000 lbs.
Vehicle B could have a Cd of 0.35 and weigh 3000 lbs.

freebeard 10-26-2020 08:54 PM

Quote:

The question is purely hypothetical so actual values do not matter.
Yes, but relative values do.

Thanks for describing the size of the ball-park. Power to weight? (not trying to be a troll)

Taylor95 10-26-2020 09:54 PM

Quote:

Originally Posted by freebeard (Post 634748)
Yes, but relative values do.

Thanks for describing the size of the ball-park. Power to weight? (not trying to be a troll)

Assume both vehicles have the same engine. An average car can put out around 180 horsepower to the crankshaft.

freebeard 10-26-2020 10:19 PM

Quote:

50/50 city and highway driving
I going to go ahead and side with JulianEdgar: testing.

aardvarcus 10-26-2020 10:29 PM

I would vote lower cD. Careful driving to minimize brake use can minimalize weight penalty. Inertia isn't the enemy until you convert it to heat.

I would also assume in real life that weight could buy you extra utility.

freebeard 10-26-2020 10:59 PM

I can't choose. You have one vote each right now.

Less weight means better 60-foot times but better Cd is going to look better. :confused: Intangibles.


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