2008 Dodge Viper Mileage: Not Appalling?

The Viper leaves our offices today after a week of me tooling around in the sinister coupe, and sitting at my desk this morning I had to tally up the gas receipts for the week. Much to my surprise, the dang thing got 20.17 mpg over the course of 750 miles, which ain’t too shabby. Of course, most of my driving was on the highway at cruising speeds, including a 170-mile road trip where, at 70 mph, the Viper was barely off idle in sixth gear. And, oh yeah, no cruise control made that driving a blast (note: sarcasm).

Official EPA estimates put the Viper at 13/22 mpg city/highway, so looking back those numbers aren’t too surprising, but they’re still impressive for a 600-hp supercar that has a gas-guzzler tax. A four-wheel-drive 2009 Honda Pilot is also rated at 22 mpg highway, but don’t take that tidbit as a direct comparison, just a fun fact. The coupe is an insanely fast car to drive on the street, but I was cautious while “testing” it, limiting blasts of acceleration and watch-the-gauge-drop fuel consumption. If you want to push it, by the time first gear is done the car will have reached or exceeded the majority of legal speed limits. Even being conservative, though, something still doesn’t compute when you say “Viper” and “20 mpg” in the same sentence.

Dodge Viper SRT10 Returns to Cars.com (KickingTires)
2008 Dodge Viper SRT10 Expert Review (Cars.com)

Comments

[George]

Variable exhaust valve timing.
+tall top gear (isn't it 50mph per 1000 rpm in 6th gear, so 70 would be 1400)

[Infosaur]

Once, a loooong time ago, someone said something about the V-10 having unexpected emissions & economy benifits over a similar displacement V-8. This was believed to be because the individual cylinders were smaller.

I'd like to see some research into a 3-4 liter V-12 with cylinder deactivation tech. At low output mode you could be running on less than 750cc. Imagine super car performance and motorcycle millage?

(Just not at the same time obviously)

[Guy]

my understanding is more cylinders is inherently less efficient, due to more surface area for friction. More cylinders usually means smoother operation, as there comes a limit to how big you can make an individual cylinder before the pistons are too big and massive for smooth operation. Remember when small 6 cyl engines were popular? They weren't more powerful or efficient than 4 cyl engines of similar displacement, but they were smoother running. Now the smallest displacement 6 cylinder engines still on the market start at about 2.7 liters, while 4 cylinder engines top out around 2.5 l. So I'm taking this to mean that years of experience have taught automakers the lesson that this is a good cutoff point between choosing 4 vs 6 cylinders as a practical matter of balancing pleasant operation and efficiency. The developing trend is to fewer cylinders with forced induction (turbo or supercharging), which seems to be further evidence that, as a general rule, more cylinders is not desirable from an efficiency standpoint.