2nd MPG Test Drive Final Numbers - Honda CRZ Forum: Honda CR-Z Hybrid Car Forums

swat49833 · 11-14-2010, 01:41 AM

On this tank it dropped to 44.9 MPG. Gas station told me he had no idea if they were getting winter fuel yet. I will try to find out if they have and report later. It may sound like a big difference, but it only comes out to about 5 MPG diff. and a total of 50 miles for the tank. But for everyone comparing MPG's, 5mpg is a pretty good diff. Could it be a diff. in the premium and reg fuel? Don't know yet...

Renato · 11-14-2010, 03:04 AM

Fuel feedstocks vary from region to region, from season to season. Typically, as you go north or the it becomes winter, petroluem refineries will process fuels for greater volatility. Volatility is just a quantification of the gas's flash point which is to say the saturation temperature for a given pressure. Between summer and winter, you might have a difference of 100 deg F or more. This causes cold starts to be very difficult with summer gas because the fuel will have a much more difficult time evaporating for engine start.

Once the engine is at operating temperature, that will not matter and engine performance will be the same.

One thing I'd note is I had a 2005 Honda Civic for a 50K miles. I noticed after the first 15k miles, my observed gas mileage improved. I started at getting 32-35 MPG, and by the time I drove from KC, MO to Baltimore, MD, I was getting 40 MPG going across Ohio. This was comparing all highway mileage. You may want to wait a bit.

11-14-2010, 01:41 AM	#1 (permalink)
swat49833 Member Join Date: Aug 2010 Posts: 122	2nd MPG Test Drive Final Numbers On this tank it dropped to 44.9 MPG. Gas station told me he had no idea if they were getting winter fuel yet. I will try to find out if they have and report later. It may sound like a big difference, but it only comes out to about 5 MPG diff. and a total of 50 miles for the tank. But for everyone comparing MPG's, 5mpg is a pretty good diff. Could it be a diff. in the premium and reg fuel? Don't know yet...

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11-14-2010, 03:04 AM	#2 (permalink)
Renato Member Join Date: Oct 2010 Posts: 53	Fuel feedstocks vary from region to region, from season to season. Typically, as you go north or the it becomes winter, petroluem refineries will process fuels for greater volatility. Volatility is just a quantification of the gas's flash point which is to say the saturation temperature for a given pressure. Between summer and winter, you might have a difference of 100 deg F or more. This causes cold starts to be very difficult with summer gas because the fuel will have a much more difficult time evaporating for engine start. Once the engine is at operating temperature, that will not matter and engine performance will be the same. One thing I'd note is I had a 2005 Honda Civic for a 50K miles. I noticed after the first 15k miles, my observed gas mileage improved. I started at getting 32-35 MPG, and by the time I drove from KC, MO to Baltimore, MD, I was getting 40 MPG going across Ohio. This was comparing all highway mileage. You may want to wait a bit.