When fed 93 octane, this pound, self-propelled wheelbarrow will crash 60 mph in 5. Power at the wheels dropped from to horsepower with the change from 93 to 87 octane. That difference seemed to grow, and we could even feel it from the driver's seat at the test track. Compared with premium fuel, regular feed sapped the F's urgency both leaving the line and in the meat of the tach sweep. The rush to 60 mph softened to a still-blistering 5.
Tapped into the Ford's CAN bus, we recorded a peak boost pressure roughly 1. The high-octane gas also helped when soft-pedaling the accelerator, elevating mph fuel economy from That won't make a financial case for running 93 octane, but then you didn't buy the expensive engine as a rational choice. You can think of this EcoBoost engine's more aggressive high-octane tune as a sort-of sport mode that can be switched on or off with every fill of its We always assumed that mid-grade fuel existed chiefly to bilk a few more dimes from the type of people who ask the dealer to undercoat their car.
Turns out it's also for owners of Fiat Chrysler's Hemi 5. With no mention of that on the fuel-filler door, though, a driver would have to read the manual to know. With just miles on the odometer and looking as if it had already been hand washed with grit sandpaper a half-dozen times, this Charger is unlikely to ever taste 93 octane again.
Oh well. The Charger's manual says 87 octane will provide "satisfactory fuel economy and performance. Similar to the BMW, the Dodge's gains on the dyno 14 horsepower and 23 lb-ft of torque translated into negligible improvement in our real-world acceleration testing.
Saddled with elephantine heft and eager to spin its rear all-season tires at launch, the Charger posted the same 4. At triple-digit speeds, the higher power on 93 octane gave the Charger an advantage measured in tenths of a second. The Dodge also posted a 0.
Just as important, the bellicose roar of the iron-block Hemi and the Charger's ability to reduce its rear tires to jungle-gym ground cover are unaffected by the fuel in the tank.
While Ford's EcoBoost F stands out as an obvious exception, the Dodge Charger's numbers make for a tidy summary of our findings. If you buy fuel with an octane rating above the manufacturer's requirement, you're likely to feel it in your wallet more than the seat of your pants. How your engine constantly invites and silences engine knock to estimate a fuel's octane rating. Your car doesn't know the octane rating of the fuel in its tank.
Instead, the engine controller calculates an inferred octane with closed-loop logic that continuously advances the ignition timing until it detects knock, which occurs when a portion of the fuel-air mixture ignites before the spark-plug-initiated flame front reaches it.
The further the computer can advance the timing without provoking knock, the higher the octane rating. During knock, the flame front travels through the combustion chamber up to 10 times quicker than the normal spark-initiated flame front. Left unchecked, these pressure waves can damage the head gasket, pistons, or cylinder head. But the occasional brief knock is a useful tool for checking that the engine is operating efficiently. If you have an older, heavier car, SUV, or truck with high-performance engines and you are experiencing engine knock, try using premium gas for a few fills to see if that fixes the problem, even if the vehicle does not call for it.
What qualifies as premium gas varies from state to state. So pay attention if you are on a cross-country road-trip or crossing state lines. One state may require a minimum octane rating of 92 to be considered premium, while another may only require Gas stations in the United States generally offer three octane grades: regular usually 87 octane , mid-grade usually 89 octane , and premium usually 91 or Check the sticker on the pump to know which you are getting.
Email Your email address will not be published. Yes, I think many manufactures are now recommending higher octanes for optimal performance.
Of course modern engines can adjust for lower octanes with the penalty of reduced performance. In most cases higher octane does not improve MPG but does provide a little better performance. This can be important when towing, hot weather, or turbo engines that are more sensitive to octane requirements.
Owners manuals are the best place to see what is required and possibly recommended for your engine. I find I get higher miles per gallon when I use any gasoline that does not have ethanol in it. When I use ethanol gasoline, my mileage drops into the 13 to 15 miles per gallon range. Do you fill up with Regular or Premium Unleaded?
Can you feel a difference in performance? Leave me a comment and letschat! March 15, What types of fuel grades for cars are there?
Is a higher octane fuel worth the price? Lauren McCarthy. Brakes: What's all that squeaking? March 29,
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