Thundertub

SOOOO many factors go into observed gas mileage.

I drive from Jacksonville, Florida to Cleveland, Ohio round trip at least once a year. It is 930 miles each way.

Jacksonville is a coastal city and thus is essentially at Sea Level and very moderate temps year 'round. I average 23.8 in mixed daily driving here, 93 octane, quality gas. Measurements on Florida flat highway road trips can see 27-28 mpg average, with short distances over 30 mpg (highest ever 5 mile stretch measurement is 33.1 mpg on a section between Jax to Daytona, and repeatable, both north and south, every time I drive it, which is about a dozen times a year).

Cleveland is at 800 feet above sea level. In between the two cities is the Appalachian Mountains with the highest highway passes approaching 4000 feet above sea level on I-77.

The trip up is fairly flat until I get to Columbia, SC. I usually refuel just north of Statesville, NC either direction. I always think I should get the best mileage for my trip on the flat, low altitude southern leg. That is NEVER the case, whether I am driving the 996, the 2007 Civic, or the '05 Jeep Grand Cherokee with HEMI.

I ALWAYS get better highway mileage on the NORTHERN half of the trip which is all mountains and hills - often by 10% better mpg. I always drive on cruise control and I don't hot foot on the interstates.

Different gas in those northern states (all of the gas I buy has 10% ethanol)? Long downhill grades exceed the long uphill grades in the computers calculations (same grades on both directions)? Regional variation in gas mixtures work better in my car up north? And what is so unique about that one section of I-95 between Jax and Daytona (for one thing there are no highway overpasses on that section)?

SSST

I usually fill up with Chevron or Shell. We have 93 octane, 10% ethanol in Houston.
Today I filled up at a Valero station. I don't know about the mileage, but dang if the car didn't feel peppier.

I don't know if it was the gas or just the fact that it was a glorious day and I had a light schedule and took the afternoon off for the first time in 3 months.

Regardless, I have noticed that certain additive packages in different brands seem to make a difference. My 335 definitely did better on Cheveron.

I'll try the Valero again to see of my initial impressing holds.

perryinva

Yep, absolutely identical to what I get. No complaints at all, really.

I don't think the ethanol is an issue, but whether or not it is oxygenated, does. When I get gas well outside of populated areas, mileage and pep is always improved.

vwillo1

15mpg peppy city, not many lights, not sure on hwy, for some odd reason I get I-29 confused with the Autobahn. 3.4 tip btw.

Pac996

If somebody knows how to leave a light slowly like a regular car can you please tell me?

shyamvenky

I just completed a looooong roadtrip from NYC to Chicago and back. Got ~27mpg. All the way on I-80, cruising at ~75-80mph (plus occasional bursts :P) and small drives around Chicago I used 93 octane fuel (~64 gals. and ~1650 miles). I'd say not bad at all for a performance car

Capt. Obvious

Pretend your naggy mom/wife/girlfriend/grandma/daughter is in the passenger seat and you don't want to listen to her complain about your driving.

Macster

Get a quote on a new clutch and a new set of tires.

Sincerely,

Macster.

BSonwine

.

I do it all the time in my Accord, but I take you meant in the Porsche... Never occurred to me to try. I guess that wasn't very helpful.

Oh and 21.8 in 10% ethanol infused mixed driving. I've checked the computer 2 or 3 times it's always been very accurate.

BSonwine

I'm very curious what you think. A Valero just opened and it nearly abuts my driveway. I put it in my Accord and Ranger. I've been reluctant to use it in Babette, the Targa.

street rod

Pac if I want to I am able to leave the clutch out slowly and when I feel it engage I hold the RPMs at 900. The car moves smoothly and slowly off the line. I also have a new clutch which helps.

Macster

Valero is not a top tier gas.

Here's a link to a list of top tier gasolines:

http://www.toptiergas.com/retailers.html

I read -- where I have forgotten -- that Varlero's refineries are designed to refine a lower grade of crude oil which of course costs less money to buy, and gives Valero greater flexibility in what crude oil it can use, but lower grade of crude oil costs more to refine and yields less gasoline per barrel of crude.

Now I realize that this doesn't necessarily mean Valero gas is bad gasoline because it starts out with lower quality (less 'sweet') crude oil base stock.

But unless it has changed, that it is not a top tier gas means I do not use Valero gas in any of my cars and I'm probably not gong to.

Sincerely,

Macster.

BSonwine

Thanks for the link. I was surprised Sunoco was not on the list. Given a choice it's what I put in.

Your correct about Valero's capabilities. In addition i have read they are the only U.S. refiner which can refine the lowest grades of oils Those capabilities also make them the largest refiner in the U.S.

washington dc porsche

2000 996 19 city 29 hwy top closed. N/A but not stock. Oh and I calculate my mileage based on the amount of gas I put in the car vs the trip mileage counter, which I set to zero at the gas station at each fill up.

fpb111

Processing a Variety of Crude Stocks
As an independent refiner, Valero does not drill for oil. It purchases a variety of feedstocks and is able to adjust its feedstock mix based on market conditions.

http://www.valero.com/OurBusiness/Pa...rBusiness.aspx

Making Products from Gasoline to Asphalt
Valero’s refineries produce gasoline, diesel, jet fuel, asphalt, petrochemicals, lubricants and other refined products.

Key to Valero’s success has been its ability to upgrade and expand refining operations to produce high-value, clean fuels from a wide variety of crude feedstocks – two-thirds of which come from discounted feedstocks.


Valero acquires crude oil from producing leases, domestic oil trading centers and ships delivering cargoes of foreign and domestic oil.
Heavy sour and residual oil; medium sour oil; and light sweet and other oil each represent about one-third of the feedstocks...