More Weight = Better MPG????

Thats what I thought initially. I was averaging about 29.5 MPG for 50/50 city/hwy driving and I thought, hey this is great! But then I bought a craftsman tool cart and put it in my rear cargo area laying flat, and I though, man this is REALLY going to kill my gas mileage...

But much to my suprise and perplexion, my MPG actually increased dramatically. Yes folks, but putting a 150lb craftsman tool cart my MPG went from 29.5 to 31.1 for the same driving distances(daily commute), same driving style (always in a hurry), and same weather conditions.

Go figure. Anybody got any ideas why I gained almost another 2 MPG by adding 150lb of weight?

 

Maybe adding the weight to the rear took some of the pressure off the drive wheels, taking less effort to get rolling? Just putting the idea out there for thought.

 

Could be you were getting a tail wind?

 

lots of different things could have helped your MPG. Extra weight could have lowered the vehicle enough to change the aerodynamics of the HHR to make it more air-efficient. Tail wind/weight off the front like JX3 said. Less than usual heavy on the loud pedal since you were paranoid about bad MPG. Differnent fuel. Temps, barometric pressure. ANYTHING could have helped this. Sometimes I can get 54mpg cruising at 35 in 5th gear for extended time periods.

 

As in a truck, adding weight to the back, over the rear tires, keeps the rear tires from 'bouncing' , this keeps more rubber on the road, = better mpg.

 

Maybe on a rear wheel drive vehicle. Adding weight to the rear of a front wheel drive eases some of the weight of the drive wheels, thusly increasing the likelyhood of bouncing and less rubber on the road.

 

Same principle tho, when the rear wheels bounce, causes resistance that could effect fuel economy.

 

I'm glad I found this thread! I thought something was wrong with the DIC read-out as I couldn't believe I got 30MPG on a recent trip.

HHRvey( an automatic) was loaded with 5 full-size adults, and one 5'3 kid in the cargo area. It was over 90 degrees the day of the trip, and the air was on full-blast! Believe me we were shocked, yet very impressed with this mpg!

Since then, when it's just my hubby and me, we get about 26 or 27mpg on a long trip. QUESTION? Should I put a large brick or something in the back to get those extra 3mpgs back?

 

Better make sure the kid gets strapped in with the cargo net!!
I'm sure a couple of subs in back will do the trick.

 

Hi Dory!
I got a good chuckle out of your reply! Actually, the kid I referred to was 17, but kind of small for his age. After he crawled into the cargo space, I packed pillows all around him along with the cargo net to keep him enclosed... kind of a car seat for grown-ups maybe?