2009 Dodge Challenger R/T: Octane in the Membrane
July 23, 2009
AFuel Octane Saga is currently swirling around our 2009 Dodge Challenger R/T. Brent Romansheard somewhere that it needed 91 octane, but he was flummoxeda few weeks ago by a fuel filler door that made no mention of a premium fuel requirement. His theory was supported by this statement on page 315 of the owner's manual:
"The 5.7L engine (with manual transmission) is designed to meet all emissions regulations and provide excellent fuel economy and performance when using high-quality premium unleaded gasoline with an octane rating of 91 or higher."
So he unleashed his mad fabrication skillz and devised a cunning warning label of his own, the results of whichyou can see above.
But the utter lack lack of afactory-installed gas-door warning that stipulated the use of 91 octane was a red flag for me. Any carmaker worried about reducing warranty claims and warranty costs (and thats ALL of them) wouldn'tdream of omitting such a warning if 91 octane were required. There might even be a legal requirement for such a label.
So I did a little investigating...
1) The owner's manual references our R/T's fuel requirement in TWO places.
a) Re-read the statement above from page 315. Nowhere does it say that 91 octane is required. It says only that 91 or higher octane will "meet all emissions regulations and provide excellent fuel economy and performance". It doesn't say thatthe engine will be damaged by the use of 87 octane regular. Sure, performance would be lower on 87, but fuel economy and emissions could easily be the same or better.
b) Page 412 is a specifications chart, the kind that tells you what kind of oil to use, etc.
Note the word "Preferred." According to this page, fuel with an octane of 91 isnot "required", They would use that word (or omit "Preferred") if they were dead seriousabout 91 octane. It's not even"recommended", the word used when there is a clear benefitassociated with91, but the use of 87 won't hurt anything.
"Preferred" seems like a word choice that makes the use of 91utterly optional. I prefer to eat at Ruth's Chris steak house or Morton's, but I can afford Sizzler or Black Angus.
2) My final bit of evidence is the actual EPA certification for this car, as documented on the EPA's website, www.fueleconomy.gov.
Manufacturers choose the fuel that willbe used for the official EPA fuel economy and emissions tests that determine the car's window sticker MPG rating and it's contribution to the parent company'sCAFE score. And make no mistake, those are high-stakes outcomes.
Ifan engine requires 91, they must use 91 for these tests. It the manufacturer thinks 91 will deliver better MPG or emissions, they'll use 91 and make it a requirement. The official EPA results are THAT important to them.
But theDodge Challenger R/T 5.7-liter V8 with a manual trans (our car) was certifed on 87 octane regular gasoline.
Want to see for yourself? Go here, and click on "2009", then "Dodge", then "Challenger", then the third line down labelled "Manual 6-spd, 8cyl, 5.7 L, Regular Gasoline SIL". Actually, you don't need to click the link because it says "regular gasoline" right there. But click it anyway and you'll see "Regular Gasoline" front and center. And that, my friends, is87 octane in EPA-speak.
To recap: a) There's no premium warning on the gas door; b) 91 octane is listed as "preferred" in one part of the manual, not required; c) another page says only that the engine will meet emissions and deliver "excellent fuel economy [Ha!] and performance" on 91 octane, and; d)this engine and transmission combination underwent officialfuel economy and emissions testson 87 octane regular.
Sorry Brent, but I'm peeling off your tape. This thing will run just fine on 87 octane. Dodge is steering us to 91 octane because that's what they used for their advertised 0-60 times and horsepower and torque claims. And we'd use it for our own track tests, too, because track tests are a measure of best performance.
But you can use 87 octane all day if that's what you can afford or if the premium pump is broken at your local station. All you stand to lose is5 or 10 horsepower.
Dan Edmunds, Director of Vehicle Testing@ 8,880 miles