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Premium gas the next step in fuel efficiency and break even point?
Too many people would run them on Regular anyway, then invoke the warranty when their engine blows a head gasket or breaks a crank at 8,000 miles. I'd be surprised if the manufacturers chanced it. So far they've only required premium for heavily-advertised "performance cars".
Here in Georgia premium is way more than 30 cents. It’s 50 cents. A few years ago it was more like 20 cents a gallon.
I've seen premium cost $0.70 to $1.20 per gallon more than regular. I drove a vehicle which took premium back when the difference was $0.20 a gallon. If you used a lower grade, the car ran like crap and burned more fuel so you didn't save anything.
Refineries want to maximize their yields, rather than produce the highest possible octane gasoline. Charles "Boss" Kettering found this out when his research resulted in the 1949 OHV Cadillac & Oldsmobile V8s. His intention was to continue to increase compression ratios, eventually resulting in smaller displacement engines that produced the same horsepower, but got better fuel economy. Perhaps he envisioned a fleet of automobiles that ran on 115/145 avgas.
As has been pointed out, we measure octane rating differently today. Regular gas is about 90 octane in today's measurement, while premium gas is 95. Super premium (Sunoco 260) was about 97-98 octane.
Refineries want to maximize their yields, rather than produce the highest possible octane gasoline. Charles "Boss" Kettering found this out when his research resulted in the 1949 OHV Cadillac & Oldsmobile V8s. His intention was to continue to increase compression ratios, eventually resulting in smaller displacement engines that produced the same horsepower, but got better fuel economy. Perhaps he envisioned a fleet of automobiles that ran on 115/145 avgas.
As has been pointed out, we measure octane rating differently today. Regular gas is about 90 octane in today's measurement, while premium gas is 95. Super premium (Sunoco 260) was about 97-98 octane.
So would an added cost of say, 30 cents for premium, if regular was 3.70, premium is 4.00, a mid-size car built for regular gets 32 mpg, and then automakers build the same car but runs on premium, same hp but less engine size, gets 36 mpg, which one actually saves more money? And what's the break even point in mpg does premium gas car make sense? Like 38+ mpg to offset the 30.cents extra in cost in premium gas?
I posted this thread and you the first person to stay in topic.
With all the turbo downsizing nowadays, the next step to reach the epa mpg standards, I do see going premium gas will be mainstream sooner or later. In older cars, with higher compression and same size engines, sometimes I see between 30-40 hp more compared to the regular gas versions. I do see in the future with turbo downsizing, carmakers will keep the same hp figures but make the engine even smaller, and with less torque they might refine or add more gears to their transmissions to make it work.
If let's say, a midsized car, turbo downsized now, gets 32 mpg on regular gas, 200 hp. If it's switched to a smaller engine, still 200 hp, but now it gets 35 mpg but on premium gas, which car is the better deal financial wise, if regular gas is 3.70, premium is 4.00?
Also what is the break even point in terms of mpg, if the regular gas car gets 32 mpg, would the break even point be at least 38 mpg to break even?
Also If there is more demand for premium gas in the future, and they mass produce it, would the price come down and be just 10 cents more than regular? I do see this as the future with mpgs going up and up. Electric cars will take a while due to the lack of lithium.
All that premium gas does, is to allow a higher compression ratio. Now for the last 20+ years, every car sold in the industrialized world has had a knock sensor, so even if you're lugging the car uphill at 20 mph in 110F heat, you won't blow little holes in the tops of your pistons, the controller will just retard ignition timing and richen the mixture to prevent detonation. When you put premium in your modern car that says it's required, all you're doing is ensuring maximum possible power under conditions that might cause detonation. If you've got a 200 HP car and you're running down the freeway at a good clip (lots of forced air cooling) and using say 40 HP to propel yourself, your car is behaving EXACTLY the same as if you had regular gas in.
Of course, turbochargers are there for the express purpose of increasing compression ratio (not mechanical compression ratio, but brake mean effective pressure). Even so, you're not going to see any significant increase in fuel mileage from going to regular to premium gas - unless you drive at max boost all the time. In which case it's not going to be gas that's your big expense, it'll be replacing turbos as those things only have a limited number of cycles on them before they start to creep under inertial load.
MPG, whether rated or actual, will always be driven by fuel efficiency at part throttle, not at full throttle max power.
So would an added cost of say, 30 cents for premium, if regular was 3.70, premium is 4.00, a mid-size car built for regular gets 32 mpg, and then automakers build the same car but runs on premium, same hp but less engine size, gets 36 mpg, which one actually saves more money? And what's the break even point in mpg does premium gas car make sense? Like 38+ mpg to offset the 30.cents extra in cost in premium gas?
I posted this thread and you the first person to stay in topic.
I have spent a lot of time looking into the effect of compression ratio on engine efficiency. However, the figures I have come across vary greatly, from not very much, to Car and Driver saying that a 1 point increase in compression ratio results in a 6% increase in performance, and an 8% increase in economy.
GM modified their vehicles in 1971 to run on unleaded gas. The compression ratio for regular gas engines was about 9:1, premium gas engines about 10.25:1 prior to this. They both went to 8.5:1 in 1971. The effect, particularly on engines that were previously premium gas, was quite significant. These less efficient engines produced more waste heat underhood, in the cooling system, and out of the exhaust pipe.
I had a 1997 Pontiac Grand Am with the quad four that I ran on 91 octane gas. I run my 2019 Buick Encore with the direct injection engine on 93 octane. If the use of premium gas would mean that I get even slightly better gas mileage, and would win at the drag strip over someone else who uses lower octane fuel, that's enough for me. I get 26 mpg on the Encore; the first vehicle I have had which matches the EPA City rating, and is better than either Consumer Reports or Car and Driver got, although to be fair to Consumer Reports, they tested the less efficient standard engine. Wooster, Ohio and Amsterdam, Holland are both red light districts, but for different reasons. So matching the EPA City rating here is an achievement.
Contrary to popular belief, more people try to save a few cents by running lower octane fuel than those of us running premium fuel when it may not be necessary. Back in the days of leaded fuel, you could hear premium fuel vehicles knocking continuously under acceleration because their owners ran regular gas.
Last edited by mshultz; 08-04-2022 at 05:51 AM..
Reason: Additonal information
With all the turbo downsizing nowadays, the next step to reach the epa mpg standards, I do see going premium gas will be mainstream sooner or later. In older cars, with higher compression and same size engines, sometimes I see between 30-40 hp more compared to the regular gas versions. I do see in the future with turbo downsizing, carmakers will keep the same hp figures but make the engine even smaller, and with less torque they might refine or add more gears to their transmissions to make it work.
If let's say, a midsized car, turbo downsized now, gets 32 mpg on regular gas, 200 hp. If it's switched to a smaller engine, still 200 hp, but now it gets 35 mpg but on premium gas, which car is the better deal financial wise, if regular gas is 3.70, premium is 4.00?
Also what is the break even point in terms of mpg, if the regular gas car gets 32 mpg, would the break even point be at least 38 mpg to break even?
Also If there is more demand for premium gas in the future, and they mass produce it, would the price come down and be just 10 cents more than regular? I do see this as the future with mpgs going up and up. Electric cars will take a while due to the lack of lithium.
Many turbocharged cars run perfectly fine on regular fuel.
If you can keep you foot out of it, I suppose a small-displacement turbo car will get better fuel economy than a normally aspirated car. However, I currently own 5 turbo charged cars and none get any better fuel economy than the equivalent NA car when driven in a similar manner. X horsepower is generally going to require the same amount of fuel regardless of whether said power is produced via turbocharging or displacement. For example, I had a 2004 Corvette Z06, which produced 400hp from it's normally aspirated 5.7 liter V8. One of my current cars is a 2021 BMW Z4 M40i, which weighs slightly more than the Z06 and has about the same HP, courtesy of a 3.0 liter 6 cylinder. The Z4 gets far worse fuel economy than the Corvette did.
So would an added cost of say, 30 cents for premium, if regular was 3.70, premium is 4.00, a mid-size car built for regular gets 32 mpg, and then automakers build the same car but runs on premium, same hp but less engine size, gets 36 mpg, which one actually saves more money? And what's the break even point in mpg does premium gas car make sense? Like 38+ mpg to offset the 30.cents extra in cost in premium gas?
I posted this thread and you the first person to stay in topic.
I think no one has answered your post because its a middle school algebra equation and they don't want to do your homework for you. ;-) Figure out your costs per mile in each scenario and compare.
Using the numbers you provided (which I think are inaccurate - even at Costco, premium (93) is $.40 higher per gallon than regular (87) and more importantly, automakers aren't usually going to make and offer an engine that is the same HP output as another - they would want there to be more differentiation.
Given the values you provided above, if there is no incremental price increase for the more efficient engine, you break even from day 1. But increase the cost of premium to a realistic number, reduce gas prices to pre-pandemic levels or reduce the "more efficient" engine by a couple of mpgs and the break even period gets much longer.
With all the turbo downsizing nowadays, the next step to reach the epa mpg standards, I do see going premium gas will be mainstream sooner or later. In older cars, with higher compression and same size engines, sometimes I see between 30-40 hp more compared to the regular gas versions. I do see in the future with turbo downsizing, carmakers will keep the same hp figures but make the engine even smaller, and with less torque they might refine or add more gears to their transmissions to make it work.
If let's say, a midsized car, turbo downsized now, gets 32 mpg on regular gas, 200 hp. If it's switched to a smaller engine, still 200 hp, but now it gets 35 mpg but on premium gas, which car is the better deal financial wise, if regular gas is 3.70, premium is 4.00?
Also what is the break even point in terms of mpg, if the regular gas car gets 32 mpg, would the break even point be at least 38 mpg to break even?
Also If there is more demand for premium gas in the future, and they mass produce it, would the price come down and be just 10 cents more than regular? I do see this as the future with mpgs going up and up. Electric cars will take a while due to the lack of lithium.
Premium fuel doesn't increase fuel economy. I've never seen a situation where paying the 90 cents more that premium costs would be worth it.
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