Junk in the trunk; excess wight impacts on fuel economy

G'day All,
Has anyone studied the impact of excess weight in the car vs fuel economy? I am thinking about the tools and stuff riding around in the trunk for emergencies and also what the impact might be of a trailer hitch that weighs 30lbs (class1) vs 55lbs. (class 3) The hitch is out of the wind so it is just a weight issue.
I do cross a couple of notable hills each day to and from work.So if I were to shed say, 20 lbs of "stuff" and 20 lbs of Pinback (the hitch is for a bike rack, so it could happen) would I see a difference?

Any old threads on this topic or experimental evidence would be appreciated.

Pinback

 

I was thinking of trying something like that, loading a bunch of old equipment or lead shielding components into the cargo area and seeing at what point I would see the impact on mileage. Probably the bike(s) on the back of the car will be more of an impact due to air resistance when at freeway speed.
I wondered about weight because the car seems to have a not so great strength to weight ratio.

That is a very interesting anecdote about the full car on mountain roads. Best ever? Humm. I guess there is a lot to be said for regenerative braking with a battery in good shape.
~50 lbs of extra hitch receiver is a very small percentage of the over all weight of the car.If I recall the density of petrol at room temp is ~6lbs/gallon (3/4 of water) a that means the receiver hitch is about the same as an 8.25 gallon fill up.

OK, I am convinced, the extra weight of the hitch will probably make no discernible difference.
Still doing the experiment with the extra weight in the back and increasing it over time would prove interesting. I have also wondered what the engineers considered when they were specifying the battery pack. I am guessing they had to ask at what point does carrying more battery capacity quit paying off due to increased weight vs capacity? Or was it about cost or volume to fit in the car neatly?

Pinback

 

G'day Leadfoot,
I think you are right, it will impact much more around town and most of my driving is on "freeways" which can feel a lot like surface street driving in LA. If my health permits me to really get back on the bike, then maybe the loss of extra personal mass will offset the weight of the receiver/hitch assembly. We'll see. And I think the additional weight is small enough to not worry about it.

Pinback