another long trip...

[studdyhalllooser]

ok....came up to livonia MI(near detroit to put things in perspective) and my mileage is confusing the crap out of me.

first tank i drove 252 miles before i filled up and took 7.1 gal to fill up...thats 35.5 m/g

second tank i drove 244 miles and took 5.58 gal to fill up....thats 43.7 m/g

third tank i drove 239 miles and took 5.73 gal to fill up....thats 41.7 m/g

735 total miles...18.41 total gal.....39.9 m/g (my last big trip over the same route got an average of 41 1/2 m/g if anyone remembers reading the thread)

i was thinking the drastic change in mileage would be due to the speed i was driving and the terrain i was driving on as well but i got to thinking about it and im confused.....the first tank was all 55 m/h highway driving with virtualy no hills....the second tank was a constant 75 thru the hills in tennessee and kentucky....and the last tank was varying between 80 and 75 thru ohio to michigan. how in the world did i get 43 m/g speeding up and down hills and only get 35 going slow on a flat road????

[Safety Guy]

That's a mystery all right.

Here's my experience driving north from Florida in an Aveo rental:

From Ormand Beach, FL to Byron GA was 33 mpg.
From there to Philadelphia, TN was 33.6 mpg.
From there to Walton, KY was 32.1 mpg.

It got colder and more hilly as I headed north.

Mine makes sense. Yours doesn't.

What about other factors? Do you fill up your tank letting the nozzle turn itself off each time? How much did you idle, perhaps waiting on traffic? Any severe weather conditions?

Your figures:

first tank...35.5 m/g

second tank...43.7 m/g

third tank...41.7 m/g

735 total miles...18.41 total gal.....39.9 m/g (my last big trip over the same route got an average of 41.5 mpg...

Only your first trip leg is significantly different. Did you recheck your math and the sales slips on fuel taken aboard? Maybe you made a mistake. I sometimes find I make a mistake and either have to redo it or throw out the results because I lost my numbers.

My guess is something went wrong on that first leg's calculations, because the others are all from 41.5 to 43.7. And that 43.7 may have been less hilly and warmer.

(Just guessing.)

Karl

[AlaskaFestivaGuy]

MPG

What about winds? Aerodynamic drag, which is already high on boxy cars like the Festiva, goes up as the square of wind speed. Just a 10mph headwind at 60mph makes the car "think" it's going 70mph aerodynamically. Drag then goes up 37% (1 10/60, squared), driving fuel consumption up for the same 60mph roadspeed.

[Safety Guy]

Good point! I forgot to mention the possibility of headwinds--and tailwinds.

Karl

[studdyhalllooser]

well....i may have wrote the wrong numbers down when left. does sound fishy not getting good mileage all of the sudden. the temp was 50's in mississippi when i left and around 30 when i got here in michigan....you get worse mileage in colder weather right?

btw...its always nice driving back into the city where everyone laughs at festivas

[studdyhalllooser]

heres the trip home....mileage suffered bc i made the 13 hour trip in 11 1/2 hours

261336 to 623 - 287 miles 8.4 gal - 34.87m/g

623 to 906 - 283 miles 8.57 gal - 33.02m/g

261906 to 262086 - 180 miles 4.46 gal - 40.35m/g

750 total miles 21.43 gal - 34.99 m/g

i coulda took my time and made better mielage but i wanted to get home so bad....the first two tanks i was doing a steady 75-80 m/h. it was loaded and it was windy as hell the whole trip....the last tank was all 60-65 m/h 2 lane country highway driving. nice to know that my 260+ thousand mile festiva made a 1500 mile trip no problem.

[Safety Guy]

Just the fact that you're driving a 200K + mile car (that can get over 33 mpg!) on long trips like these should be nice enough!

My B6 is running real nice in my 165K+ mile GL, but I need to redo my suspension due to bad front strut bearings. As soon as I have it done I'll have no problem doing state to state trips either. Most of them won't be over 1000 miles though!

Karl