Premium vs Regular Fuel

[Tom N]

I've been running my 2019 TourX Essence on premium fuel since it was new. With fuel prices out of control I started to run on regular fuel to save 50 to 60 cents per gallon. I haven't noticed any difference in normal driving. I would appreciate any comments from members who have been running regular fuel routinely. Thanks

 

[Rk54Strat]

I’ve owned a new ‘19 TourX Essence since 2020 and it now has 34k on it. I’ve never used premium fuel and I haven’t noticed anything lacking in the cars performance.

 

[saab93driver]

I've run both in mine over past almost 3 years / 48K miles. I have never seen any difference in how the car drives on regular vs premium.

 

[wi_badger]

Have a 2018 and have only used premium since new. In a previous car that recommended premium I would sometimes use 87 octane when 93 wasn't available. Those tanks would have a drop in gas mileage of 10% - 15% which was more than the savings per gallon. Not sure if the TourX exhibits the same behavior but keep track of mileage in addition to the general feel of performance. In most cases I suspect its fine and the different would only be noticable when doing long, steep, uphill grades, high altitudes, or heavy loads. Might notice more engine knock/ping.

 

[PrincipalDan]

I live at high altitude (6,500 to 6,700 ft on a regular basis) and have always used the highest octane I can get my hands on (91 octane in my little town.)

I use the throttle pretty regularly and don't want to risk anything with the engine. I've been trying not to push past the "dent" in the gas pedal with prices so high. I must admit though I may be giving a hybrid serious consideration for my next vehicle.

 

[D2R]

I’ve owned a new ‘19 TourX Essence since 2020 and it now has 34k on it. I’ve never used premium fuel and I haven’t noticed anything lacking in the cars performance.

Hey, wait a second there, mate. 🤣
If you have never used premium fuel, how do you notice anything lacking in the car's performance? 😛
Not trying to criticize or anything, but that statement is not making sense though.

 

[ulycyc]

Most cars are tuned from the factory at sea-level. At higher altitudes the air is thinner so you need less octane. You can get away with a few points less of octane. This is why some can get away with it and some can't based on your location. Colorado compared with NYC could be a few thousand feet difference. Premium fuel cars can drop to 87oct in some cases in Colorado. This also could vary by temps, pressure and humidity. When I race we use a weather station to adjust octane and stotch. At sea level we use C16 (116oct) in Ohio we use 114oct or 112oct

 

[Rk54Strat]

Hey, wait a second there, mate. 🤣
If you have never used premium fuel, how do you notice anything lacking in the car's performance? 😛
Not trying to criticize or anything, but that statement is not making sense though.

No worries Bro- not trying to correct you or your criticism but the original question as stated didn’t actually ask for comparisons from folks who ran premium and or regular- just observations from people who are using regular. Reading comprehension counts. 🧐

 

[Jmlo96]

I may consider starting to run 87 or 88 E15 in my Regal as well. Running 88 I haven't noticed a great difference from 93. This car doesn't get great MPG in my local driving (I've been seeing 17-20 mpg) so running 93 at current prices is definitely an ouch.

 

[bollox74]

pretty much at seal level here in Savannah GA and I run 89 daily, especially as costs remain high. In town driving & tire choice have more impact than octane from my experience.

 

[L J]

I've run both in mine over past almost 3 years / 48K miles. I have never seen any difference in how the car drives on regular vs premium.

I assume your burning reg. grade then, since price spread between grades is getting much larger.

 

[saab93driver]

I assume your burning reg. grade then, since price spread between grades is getting much larger.

I experimented a while before the current situation so I've been burning regular for a bit longer. I guess if the spread was 20 cents I might not care but those days were gone a while ago.
.

 

[ready2fly]

I have no idea how you guys don't notice any difference. I notice a huge difference when I fill up with regular. Acceleration is sluggish, I lose around 2-3 MPG on regular gas vs premium. Furthermore, I tried to fill up with racing fuel 100 octane once (which burned exhaust sensors, so don't do it), but my MPG improved to 30-33 in mixed city driving, which is amazing (I usually get 24-26 MPG). Acceleration also felt like I had an extra 50 horses added to my engine.
I go for premium every time. Our cars are still way more fuel efficient than Jeep Wranglers and F-250's that most "cool kids" seem to be buying these days. Power/performance-fuel efficiency on the Regal is almost perfect for its size and price.

 

[PrincipalDan]

I have no idea how you guys don't notice any difference. I notice a huge difference when I fill up with regular. Acceleration is sluggish, I lose around 2-3 MPG on regular gas vs premium. Furthermore, I tried to fill up with racing fuel 100 octane once (which burned exhaust sensors, so don't do it), but my MPG improved to 30-33 in mixed city driving, which is amazing (I usually get 24-26 MPG). Acceleration also felt like I had an extra 50 horses added to my engine.
I go for premium every time. Our cars are still way more fuel efficient than Jeep Wranglers and F-250's that most "cool kids" seem to be buying these days. Power/performance-fuel efficiency on the Regal is almost perfect for its size and price.

At least with the AWD TourX models the issue I have is the HUGE gap between city and highway fuel economy. I've hit 30 easily on the interstate even running at 80 mph, in the city being able to get 23 mpg is a good day. When I was working a job that required lots of stop and go just to get the front door of the building I got as low as 18 mpg in the winter. I do wonder if there would have been any difference if all models had gotten the 9 speed auto.

Driving my TourX from Gallup to Albuquerque feels like getting a marathoner out on a course, and feels like you are making the machine "happy".

 

[ready2fly]

At least with the AWD TourX models the issue I have is the HUGE gap between city and highway fuel economy. I've hit 30 easily on the interstate even running at 80 mph, in the city being able to get 23 mpg is a good day. When I was working a job that required lots of stop and go just to get the front door of the building I got as low as 18 mpg in the winter. I do wonder if there would have been any difference if all models had gotten the 9 speed auto.

Driving my TourX from Gallup to Albuquerque feels like getting a marathoner out on a course, and feels like you are making the machine "happy".

Exactly why I did not get TourX - paying extra for AWD, paying extra for gas, paying extra in case AWD ever fails and you get 8-speed instead of 9-speed. Sportback still has a huge trunk.

 

[autocomman]

You should really just be filling the tank with what the manufacturer recommends. I hate to say it but there's reasons for it. Now you can use regular, but it's going to retard timing, especially in a boosted engine. You retard timing your mileage goes down. Also it's retarding timing because the engine's knocking, even though you can't hear it, it is and it does. And long-term it's really not great for the engine. And like I said it's retarding timing, whether you feel it or not that is exactly what it is doing. Those are just the facts Jack. So the couple bucks your saving at the pump, are you really saving it in the end? Now if it required regular, and you're putting premium in it then you're throwing money down the drain. But the car was tuned on premium you really should be running premium. Otherwise you should have bought a different car. Just one man's opinion. And the nine speed isn't really going to get you anything over the 8th speed transmission. I don't know what the final drive ratio is but I imagine it's probably not that different. I've gotten 29 miles a gallon consistently at 80 miles an hour with the cruise on. If I drive 70 it'll go well into the 30s no problem. Around town it can vary between 23 and 26 or so depending on how angry I am at everyone around me, haha

But if you want to put regular in it and get better mileage, go get an encore. This three cylinder POS I've had as a dealer loaner for the last month will actually get high 20s with me driving it like an a-hole, It will go into the 40s if I drive 70. I just want my GD car back, can you tell?

 

[eccs19]

My 2 cents on this. I've mostly run high ocatane fuel, but with the prices of fuel so high, I've switched to regular. Mileage, I've not noticed that much difference, but it's winter here, and car's mileage always drops for my when it's below freezing, but performance wise, I do notice a difference, especially at about 3/4 throttle. Car just doesn't have the same pep on regular. Enough that when I first switched, I kind of forgot and pulled into traffic and was thinking there was an issue with the car, but then remembered the fuel change. I have done a tank at one point back at premium fuel, and car woke back up. Then next tank back with regular fuel, car was a slug again.

 

[adam728]

I always run premium, typically 93 octane from Murphy (Walmart). Wife took over the car for 5 months while we waited for her VW to get fixed. She refuses to spend extra for premium or midgrade.

When I drive I typically have my cell phone on a windshield mount displaying a few OBD parameters though the "Torque" app. One of those being knock retard. On a across-the-state trip I locked cruise at 80 mph and noticed something funny. Knock retard was almost always pulling 2-3 degrees of timing. It would taper out, then jump right back in. I asked the wife if she filled with regular, to which she responded "how did you know?". I've never seen it pulling timing at a constant cruise like that with premium.

I also notice that under wide open throttle knock retard often jumps to 2-3 degrees with premium. I've seen 7 degrees with regular fuel!

Can't really compare economy. Her and I drive much differently, and she never records miles, gallons, gets a reciept, etc. Also, I've said it before, calculate mileage. The computer is trying it's best to calculate it, but isn't 100% accurate. Looking at my log right now, in 14,501 miles logged I have averaged 24.50 mpg. I mark down the Trip A mpg and reset each time, those tally up to 25.76 mpg. So about 5% optimistic.

 

[Jmlo96]

I always run premium, typically 93 octane from Murphy (Walmart). Wife took over the car for 5 months while we waited for her VW to get fixed. She refuses to spend extra for premium or midgrade.

When I drive I typically have my cell phone on a windshield mount displaying a few OBD parameters though the "Torque" app. One of those being knock retard. On a across-the-state trip I locked cruise at 80 mph and noticed something funny. Knock retard was almost always pulling 2-3 degrees of timing. It would taper out, then jump right back in. I asked the wife if she filled with regular, to which she responded "how did you know?". I've never seen it pulling timing at a constant cruise like that with premium.

I also notice that under wide open throttle knock retard often jumps to 2-3 degrees with premium. I've seen 7 degrees with regular fuel!

Can't really compare economy. Her and I drive much differently, and she never records miles, gallons, gets a reciept, etc. Also, I've said it before, calculate mileage. The computer is trying it's best to calculate it, but isn't 100% accurate. Looking at my log right now, in 14,501 miles logged I have averaged 24.50 mpg. I mark down the Trip A mpg and reset each time, those tally up to 25.76 mpg. So about 5% optimistic.

Can't beat real world technical results. That's a pretty significant jump. What types of temperatures were you seeing when this was occurring? If this was in cooler weather, I can only imagine what would happen with higher heat.

 

[L J]

Can't beat real world technical results. That's a pretty significant jump. What types of temperatures were you seeing when this was occurring? If this was in cooler weather, I can only imagine what would happen with higher heat.

Not driving TourX since last year, but it does run better on 91. But if only 5% difference in mileage that is not gonna cover the spread in price.
I have been burning regular in LS3 in G8 and it seems to run fine on it. Much easier to not mind power loss when you have plenty to start with.