Commentary

Generally speaking, the heavier a car is, the more power is needed to get it moving.  The more powerful the engine is, the more gas it uses.  So auto makers face a trade-off between making their cars faster or more fuel efficient.

Here is what the automakers have done over the past 8 years with select models.  First the Japanese (% increase or decrease in horsepower, curb weight and EPA gas mileage):

As you can see, Toyota has been able to increase the power and weight of the Camry while also improving the fuel economy.  Neat trick.  Honda, comfortable with the fuel economy of their minivan, added just weight and power.

What about The Ultimate Driving Machine?

Now the Americans.  Are you expecting a grim picture of cars getting heavier and fuel economy flat?

Did Jeep benefit from some German technology (Chrysler/Jeep was bought by Mercedes-Benz)?  They were able to increase weight, power and fuel economy, just like Toyota. 

The Chevy Tahoe doesn’t look as rosy.

Let's take a look at Ford:

Of particular concern is the Explorer which reduced fuel economy while making the Explorer heavier and more powerful.

One thing is clear, car technology has been changing.  In the absence of federally mandated fuel economy increases, the car manufacturers are making their own decisions.  I, for one, would like to see more bias towards fuel economy than weight and power.

[graphs: energyrace.com, data source: edmunds.com]