SOLD: 2009 Scion xD - BRM, 16" alloys, VSC, K&N drop-in air filter, Thule Aero roof bars, TRD sway bar, TRD short shift, TYC LED tails, Curt class-1 tow hitch, Italian leather shift & brake boots, Red Line MT-90 in the trans, Amsoil 0w20 in the engine, ATE SuperBlue Racing brake fluid.
2 bars left and the dash says 36.4 mpg. City and highway for me. This is still my complimentary tank of gas from the dealership. If this is what I will average on my weekly commute and weekend driving I will be very happy with my choice. I have only had the car 6 days.
SOLD: 2009 Scion xD - BRM, 16" alloys, VSC, K&N drop-in air filter, Thule Aero roof bars, TRD sway bar, TRD short shift, TYC LED tails, Curt class-1 tow hitch, Italian leather shift & brake boots, Red Line MT-90 in the trans, Amsoil 0w20 in the engine, ATE SuperBlue Racing brake fluid.
Interesting. I've always heard the exact opposite but never any explanation or proof, but in doing some googling (inspired by your post) you seem to be correct.
Unless you've done an engine swap, an xD doesn't have a VVTLi engine. We have VVTi -- no valve lift adjutment. Yes, there is a VVTLi version of this engine available... for instance, in the Lotus Elise.
Our engines have nowhere near the compression that requires or gains any benefit from premium gas. Regular gas ignites easier, and is what most engines are designed for. Engines with higher compression use premium and usually produce more horsepower... but it is due to the engine, not the gas. Premium gas is used ONLY to eliminate preignition (knocking) in high compression engines.
SOLD: 2009 Scion xD - BRM, 16" alloys, VSC, K&N drop-in air filter, Thule Aero roof bars, TRD sway bar, TRD short shift, TYC LED tails, Curt class-1 tow hitch, Italian leather shift & brake boots, Red Line MT-90 in the trans, Amsoil 0w20 in the engine, ATE SuperBlue Racing brake fluid.
Unless you've done an engine swap, an xD doesn't have a VVTLi engine. We have VVTi -- no valve lift adjutment. Yes, there is a VVTLi version of this engine available... for instance, in the Lotus Elise.
Our engines have nowhere near the compression that requires or gains any benefit from premium gas. Regular gas ignites easier, and is what most engines are designed for. Engines with higher compression use premium and usually produce more horsepower... but it is due to the engine, not the gas. Premium gas is used ONLY to eliminate preignition (knocking) in high compression engines.
Interesting; I read a piece on Spitfire Fighters in WWII. A great fighter but needed more climb to go head to head with the Me109. The US started supplying fuel at 100 octane rather than 89 which improved the HP of the Spitfire and gave the pilots a little edge in the Battle for Britain. I have put racing fuel in my Hyundai before and noticed a significant increase in power.
If your engine is knocking, you'll get a CEL. Unless that is happening, there should be no benefit to premium gas in our engines. "Butt dynos" are not very well calibrated. Your car might "feel" different with premium gas, but I doubt there is more power. There is no reason there should be more power. There is a good reason there should be less power: there are fewer BTUs per gallon in premium than in regular. By a very small amount, though... probably less than most people could detect.
Running premium will not hurt your engine... it just won't have any benefits, all else being equal. There is a catch there... because all else might not be equal. There may be other additives in the premium, or it may be a different brand than you usually use. I suspect that it is mostly a placebo effect. If anyone has dyne numbers that show otherwise, I will listen.
The same thing happens with biodiesel vs. regular diesel. Biodiesel has a lower BTU content. A given engine will have lower fuel economy and lower power on biodiesel, but many people report having more power. The reason is mainly that biodiesel makes the engine run quieter, so it seems like it isn't working as hard. The difference is small... but lower BTU content equals lower power. This is the same reason that E85 returns much lower fuel economy than regular gasoline or E10. Ethanol has a much lower BTU content than gasoline.
SOLD: 2009 Scion xD - BRM, 16" alloys, VSC, K&N drop-in air filter, Thule Aero roof bars, TRD sway bar, TRD short shift, TYC LED tails, Curt class-1 tow hitch, Italian leather shift & brake boots, Red Line MT-90 in the trans, Amsoil 0w20 in the engine, ATE SuperBlue Racing brake fluid.
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