Gas Milage figures from a F50. Slower is better

[PIONEER]

Hope everyone had a Safe 4th weekend.

went out of town myself, but it was too hot here in NC.

Took some Gas consumption Numbers from the Q on the Hwy. This was all done over 18-20miles of Flat Hwy per segment.

consumed Miles per gallon @ Speed Miles Per Hour A/C ON

21.9MPG @ 80MPH

24.2MPG @ 75MPH

26.5MPG @ 70MPH

27.3MPG @ 65MPH

28.1MPG @ 55MPH ( this was done for 5miles b/c the speed limit was 65mph)

[Jesda]

Man, that revised grille really enhances the look of the F50, especially on a black one like yours.

Report back and tell us what your fuel economy is at 100.

[PIONEER]

Man, that revised grille really enhances the look of the F50, especially on a black one like yours.

Report back and tell us what your fuel economy is at 100.

I think the cruise only goes up to 90. After that you'r on your own.

[Q45tech]

Every rpm requires 4 squirts of fuel and as long as you are in closed loop [14.1-14.7 AF Ratio] the squirts are an equal volume [over 1700-3500 rpm].

At light loads the horsepwer goes up as the rpms go up, so obviously the fuel consumption.

Always a better method to measure fuel use per hour [of flight so to speak]. Pounds per hour ~~15 pounds.

Next time try the same test with AC off.

Just because the speed limit is 65 doesn't mean you have to waste gasoline..................bring back 55 and watch the murder rate go up.http://www.cato.org/pubs/pas/pa-346es.html

[Skibane]

There are times when 55-60 suits me just fine - Sometimes, it's kind of nice to set the cruise and let everyone else duke it out over possession of the left lane...

[CrimsonQ]

Wow thats a huge difference between 65 and 80. thanks for posting that

[szh]

This is from an old post of mine, with a similar test of my 2003 M45. Same engine, so the results should be similar, and they are!

Hi, all.

I was coming back from San Francisco tonight, and traffic was light, so I tried to do a very simplistic mileage test using the built-in MPG measuring system.

(As a side note, I remembered a factoid from my 1991 Q45: once the cruise control is engaged, each click of the Set button reduces the speed setting by 1 mph, and each click of the Reset/Accel button increases the setting by 1 mph. Sure enough, it works the same on my M45 and the speed setting were exact (reading the speedo carefully, of course). Cool!

Anyway, here is what I did:

* Starting at 60 mph, * I set the cruise control in 5 mph increments from 60 mph to 80 mph, * let the car settle into the speed for about a mile, * reset the MPG counter, * recorded the average MPG after 5 miles. * If the road wasn't reasonably flat in that 5 mile section, I would reset the counter and go for another 5 miles.

Here are the results and they are kinda interesting and confusing at the same time!

* Indicated 60 mph: 29.1 mpg * Indicated 65 mph: 27.0 mpg * Indicated 70 mph: 25.6 mpg * Indicated 75 mph: 23.2 mpg * Indicated 80 mph: 23.2 mpg

What is interesting (peculiar?) is the slightly higher than expected reading at 70 mph (off the slope), and the lack of a real change from 75 to 80 mph!

Note that, at a steady 65mph, the M45 met its CAFE "mileage" of 27mpg for highway driving! Also cool!

Anyone have any explanations for this? Is it some gearing/engine-power/something-else anomaly?

I think I have going to have to repeat this test someday over a wider range of speeds!

Z

[Q45tech]

Highway CAFE/EPA is measured at 55 mph and never to exceed 61 mph. [even in passing].

Not sure of the question fuel use goes up at the ratio of rpm use PLUS the amount of additional HP required to overcome added wind drag at the higher speed.

THE BSFC [from HP/drag requirement] is not linear, but nothing like a boat which can consume 3 times the fuel weight per hour in just doubling the speed from 22 to 44 mph see graph.

Careful the mpg computer program is not very accurate [say +- 4%] as it attempts to correlate rpms vs load vs lab dyno numbers............real road and tire inflation variables............give or take 1 mpg is about all you can hope.

[mcrews]

Q45tech.....you are one smart man!!!!!Thank you for humoring us as we play with the gagets in our cars!!!!

So 2002 Q45 sport 255x45x18 at 65 mph driving west on hgwy 80 to San Fran 27mpg at 65 cruise set....then I got a little upgrade (very little) and dropped to 26.8mpg.I have gotten 23+ on the round trip sacramento to San Fran 170 miles, with out really paying attention

[Jeff Williams]

Sometimes I like to drive 55 as well.

If it wasn't for all those $#%* kids and speed breakers in the neighborhood, it would be fine.

[maxnix]

I think what is really interesting is the mileage at 110 mph.

Seems to be above 15 in the G50.