My 2013 Rogue is a year old this month and currently has slightly under 14,000 miles. The vast majority of gas I've been burning has been Gulf, Getty, or Sunoco, none of which are listed as participating merchants on
toptiergas.com.
Out of over 30 fill ups, maybe five of them in total were at Mobil, Shell, or BP. The rest were all "bad" gas.
Then in July, I filled up at a Shell station, where the detergents are not only supposedly better in both quality and quantity than minimum federal standards, but there's also a higher nitrogen content than other brands. For the first half of burning this tank of Shell fuel, my economy went down. I first attributed it to a higher volume of nitrogen, which takes the place of fuel cells that can actually be burned. But I think I was wrong.
I think during the first 200 or so miles, the detergents in that gas cleaned out deposits that had built up, and then the economy while burning the second half of the tank got remarkably better, so much that the overall economy for the full tank was still greater than anything I'd been getting previously.
So all this was nice, but I wasn't done. I've always felt that running Chevron techron complete fuel system cleaner once every 10,000 miles is a good idea regardless of what kind of gas the car has been burning. And also, in spite of all grades of Shell gas having the minimum amount of detergents required to qualify as "top tier," their V-power 93 octane has even more detergents than their 87 and 89 octane grades. And in spite of knowing that higher octane should not result in better fuel economy, I just wanted to see what would happen.
On my next fill up, I first poured the Chevron techron 20oz bottle into the tank. Then I put in nine gallons of V-power, and then topped it off with seven gallons of regular. This resulted in a nice mix in the tank, averaging out to about 90 octane overall and loaded with detergents from two of the better quality gas distributors in the country.
Result: My first 500-mile tank. Actually I got 508 miles, and the miles-to-empty indicator, which shuts off as soon as there are fewer than 20 MTE, didn't shut off until I'd driven either 492 or 493 miles. So I still had about 4 miles remaining according to the MTE gauge when I filled up.
Again this was at a Shell station, but I used no additive and I put in all regular 87 octane. It took 17 gallons and did not spill over. When I started the engine, the gauge told me I have 392 miles to empty. I've now driven over 100 miles on this tank, and the needle hasn't moved yet. The MTE gauge is now telling me I can drive 335 more miles before my next fill up. In other words, I'm well on my way to another 500-mile tank.
Granted, I'm babying the pedals like I've never done before and using cruise control on any road I can, but I think there's something to burning the cleanest gas you can find. My MPG gauge hasn't been reset since the spring, probably about 5000 miles ago, and I've slowly watched it increase up to 29.1. It briefly displayed 29.2 on my way to work this morning, but my office is at the top of a hill, and it dropped back down as I was parking.
A large majority of my driving is on the highway, but it's impossible to stay completely on the highway while doing my daily commute. I reset the average speed gauge at the same time when I last reset the MPG gauge, and my average speed while getting 29.1 MPG (according to the gauge) is 42 MPH. I don't remember the exact date that happened, but I think it was in mid-April. According to fuelly, if I only look at gas purchased in June, July, and August, I've been getting 27.7 MPG based on actual gallons and actual miles. I think that's impressive for a truck that's rated at 22/27 and was rated the previous year at 22/26 without any major changes.