2010 Volkswagen GTI: Don't Shoot the Messenger
March 15, 2011
There was a great disturbance in the force yesterday when I wrote that the 2010 Volkswagen GTI doesn't require premium gasoline, and that -- horrors -- I'd used regular unleaded in the car. I expected someone from Automotive Protective Services to show up and take the innocent little vehicle into foster car because of my alleged abuse.
One reader pointed us to a photo of the label in fuel filler flap as evidence that premium is required. Here's the label in our GTI, and while I don't want to parse its meaning like some kind of amateur attorney, I will point out that it says "unleaded fuel only." Not "premium unleaded fuel only."
See the exclamation-point-on-page icon? It's telling us to go the owner's manual for more information. Let's go.
Here, on page 3.3-36, it says that the label in the filler flap shows the "recommended gasoline octane rating." Recommended--not required. Is it strongly recommended? I'd say yes, but it's not "required."
And that's why the car is on Edmunds' big list of "premium recommended" vehicles. Our data team gets this information directly from the manufacturers. You won't find the 2010 Volkswagen GTI on our "premium required" list. In fact, there are no 2010 Volkswagen models on that list.
In addition to much castigation, yesterday's post did draw some interesting comments and observations about what happens if you step down from premium. Here's one:
"Please correct me if I'm wrong, but I believe that fuel economy also goes down a bit when the vehicle adjusts to a lower grade. At 25 mpg and 4.00 regular / 4.20 premium, let's say the car drops 1 mpg on regular. With premium, your costs (1/25 * 4.2) are 16.8 cents per mile, with regular (1/24 * 4) it's 16.7 cents per mile. On 10 gallons of fuel, you've saved yourself less than 2 cents ((.168 * 250) - (.167 * 240) =1.92)."
Our engineering editor, Jason Kavanagh, was kind enough to respond:
"It is true that lower octane can reduce efficiency. It depends on the engine. For example, the efficiency of boosted cars at higher load is more sensitive to octane than that of a normally aspirated car. Many normally aspirated cars will suffer no significant efficiency penalty from the lower octane.
"In other words, in a boosted car, the harder you use the pedal, the more the efficiency penalty will come into play. However, if youre the kind of person looking to save some money by using lower octane fuel, youre very likely also the kind of person who is driving conservatively, too, in order to save fuel/money.
"In this case i.e. conservative driving the efficiency penalty of lower octane fuel wont be as prominent. Depending on your driving style, you might not measure any fuel economy impact even in a boosted car. Youre more likely to see the impact in city driving in a boosted car. Freeway driving involves long periods where the engine load never strays into a region where octane is a factor. Here, too, you might never measure a fuel economy impact at all."
If you want more on the required vs. recommended discussion, please check out this excellent article.There are trade-offs to the decision to use regular unleaded instead of premium. But if premium is not required, you won't kill your car. Not by a longshot.
Carroll Lachnit, Features Editor @21,664 miles