12 September 2005

Modern Cars

As I'm sure we're all sick of hearing by now, the last time gas cost this much (adjusted for inflation) was in 1981. At the time, cars got 21 mpg. Today, the average car gets 21 mpg. No, that's not a typo. Despite all the wonders of technology, today's cars have the same fuel efficiency as they did 24 years ago. Why is that? SUVs. The increased weight (and probably air resistance too) make up for the best the automotive industry decided to dish out in fuel efficienct technolgy.

Despite making that good point, the article upon which I based this post goes on to throw meaningless numbers at the reader.

Light trucks, a category that includes SUVs and minivans, now account for 50 percent of passenger vehicles sold in the U.S. That's more than double their share in 1981.1
Large SUV sales are 11.2 percent lower than they were at this time last year, according to AutoData.2
Top speed has also increased from 112 miles per hour in 1981 to 136 mph today.3
Overall, the basic 5.7 liter Hemi V8 engine is about 10 percent more efficient than the engine it replaced. The addition of "multi-displacement" technology, which shuts off four cylinders when their power is not added, as in steady highway cruising, boosted efficiency by another 10 percent.4


  1. Do they mean double the percentage from 1981, or double the raw number from 1981? The former is more meaniningful, as simple increase in purchasing will change the latter without showing if people prefer SUVs or cars.

  2. Ditto, but more so: percent of vehicles sold, number of vehicles sold, percent of dollars spent, amount of dollars spent? Amount of dollars spent would decrease if they simply decreased the price of SUVs.

  3. From context, they mean average top speed, not top top speed, but still, who really drives their cars at top speed?

  4. Hey wait a sec, they just said it increased by 10% overall, and then they said it was an additional 10% on top of that? That's not even a mistake I'll let my developmental math kids get away with. On the other hand, maybe they meant that the engine just by itself is 10% more efficent, and the "multi-displacement technology" makes it 10% more efficient on top of that. If so, it's even more a case of sloppy reporting - the description didn't really say that, and for that second 10%, 10% of what?, the original engine or the modified engine? (Though it doesn't matter order-of-magnitude, science reporters rarely understand that concept.)

This isn't even a science article, it's a cars article, and the little evidence they throw in to try and make it more scientific goes awry.

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