Gas Data for my 2005 Acura TSX 5AT

I'm a pretty scientific person. I like collecting data and analyzing it. For about a year and a half, I have been collecting my gas data. How much I pay, how many miles per gallon (mpg) I get, simple cost per mile, and etc. Well, today I'm going to present you with my results.

The following data was collected from July 26, 2006 to Dec. 22, 2007. My favorite gas station is Chevron. I filled up 30 times at a Chevron. Shell is in second place, but I don't like going there because of the one time I got "ripped" off by them. I used Shell 6 times in the last year and a half. 76 is third place, but I didn't fill up with 76 once for the past year and a half. All the other stations I don't care for too much: Exxon (3 times), Mobile (0 times), and etc.

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Of the 39 times I filled up, all were premium (91) grade except for 9 times when I used just plus (89) grade. I would only put in plus when gas prices are outrageous, otherwise I would put in the recommended premium. Therefore, I used premium grade gas 77% of the time and plus grade 23% of the time. I wouldn't use premium at all if I had a choice, but my Acura TSX "requires" premium, even says so on the gas cap cover. =P

Price/Gallon:
Most expensive = $3.60 (Premium) on May 17, 2007 @ Chevron
Least expensive = $2.56 (Premium) on Oct 30, 2006 @ Exxon
Average = $3.14



Miles/Gallon:
Most: 23.91 miles/gallon
Least: 20.32 miles/gallon
Average: 22.15 miles/gallon



Simple Cost per Mile (price/gallon divided by miles/gallon):
Most expensive: $0.17
Least expensive: $0.11
Average: $0.14

Most miles on a tank before refilling: 310 miles (with about 4.052 gallons before complete empty). So ideally, I could get 20.32 * 4.052 = 82.34 miles + 310 miles for a grand total of 392.34 miles. Average miles on a tank before I refill = 268.60.

Comments: I have not doubt in my mind that my car can get 30+ mpg cruising on an empty highway, problem is I'm rarely doing that (gotta take a road trip in my car one of these days ;) ). The automatic Acura TSX is rated for at least 30+ mpg on the freeway, but every time I'm on the freeway, I'm stuck in morning rush hour traffic... or evening rush hour traffic. As you can probably understand by now, sitting still on the freeway won't get me more mileage than sitting still in the city. Sitting still anywhere results in ZERO mpg! These are my real life gas results.

There were a couple instances throughout the past year and a half where I got some Speed Racer spirit inside of me and pushed my car hard, may it be using the tiptronic shift or not. Usually when using the tiptronic, I'm pushing the car extra hard, revving towards redline and into the VTEC range. Enjoying driving like this results in very poor gas mileage.

After reading this USA Today article, I don't feel as bad putting in 89 instead of 91... maybe I'll start doing that more often this year. But if I really think about it, that will only save me at most about $200 a year, which isn't all that much. Skimming on gas to save $200 a year on something that I use everyday and hope to still use 10 years from now isn't so logical.

2005 Acura TSX Performance Specs:

Engine: 2.4 liters in-line 4 cylinder VTEC engine with double overhead cam, four valves per cylinder, and multi-point injection fuel system.

Power: 200 HP SAE @ 6,800 rpm
Torque: 166 ft lb @ 4,500 rpm

Recommended Fuel: Premium unleaded fuel 91

EPA Fuel Economy: highway (mpg) - 31 / city (mpg) - 22

Fuel Tank Size: 17.2 gallons

For the full specs on the 2005 Acura TSX

Here is a thread at Acurazine.com discussing driver's real world mileage for the Acura TSX.

Can I Use Regular Unleaded In My Acura?

This is straight from the Winter 2008 Acura Style magazine:

"Acura's Client Services (ACS) has thoughts on ill-advised owner attempts to beat stratospheric premium fuel prices by using regular unleaded instead. In a word: don't. Your Acura is designed to operate on 91 octane premium unleaded gasoline. If you're stranded and can't access premium, then 87 octane regular unleaded will see you home, but don't make a habit of using regular gasoline. You want the best possible performance from your Acura-and peak performance demands the correct fuel."

Here is a USAToday.com article on using Regular Vs. Premium gas. Highlights include:

"I personally use regular even though my owner's manual says you'll get better performance with premium," says Lewis Gibbs, consulting engineer and 45-year veteran at Chevron oil company. He's chairman of Technical Committee 7 on Fuels, part of the Society of Automotive Engineers (SAE) Fuels & Lubricants Council. Gibbs knows gas.
The main advantage of premium-grade gas is that it allows automakers to advertise a few more horsepower by designing and tuning engines to take advantage of premium's anti-knock properties. But auto engineers generally agree that if you use regular in a premium engine, the power loss is so slight, most drivers can't tell.

"I go back and forth, and I'm hard-pressed to notice" whether there's regular or premium in the tank, says Jeff Jetter, principal chemist at Honda Research and Development Americas. He drives an Acura designed for premium.Import brands, especially, use premium fuel to distinguish their upmarket models. Most Toyotas, for instance, are designed to run on regular or midgrade, while the automaker's Lexus luxury brand prefers premium. Same with Honda and its Acura luxury line.

Today's engines use highly evolved versions of a device called a knock sensor to adjust settings automatically for low-octane gas. And more engine control computers have adequate memory to allow separate sets of instructions for various octanes. The engine control computers keep pushing to maximize performance on whatever grade of fuel is used.

The only modern engines that should really need premium are those with superchargers, which force-feed fuel into the cylinders. "You're driving along and just tramp the gas and the knock sensor cannot sense the knock fast enough in some cases," because the supercharger boosts pressure so fast, says Bob Furey, chemist and fuels specialist at General Motors.

Burning regular when the owner's manual specifies premium won't void the warranty, nor damage the engine, even the most finicky automakers say. "You're giving up perhaps just a little bit of performance that a customer wouldn't really even notice, it's so slight," says Furey.

Automakers say they don't test premium engines on regular to check the difference, but some auto engineers estimate that power declines roughly 5%.