35 - 40 MPG !!!

[Erebus]

Hydrogen would make the even LIGHTER!

Yah, so you put helium in the front tires to move the front/rear balance of weight to the back -- although hydrogen would be even better, it is even lighter.

But the rear tires should have depleted uranium in them. Would again help move the weight balance to close to 50/50. Would also free up cargo space, since you wouldn't need those sandbags in the back. And since everyone knows depleted uranium ammunition goes through everything, then by extension DU-filled tires should mean you can now go through everything, you'll never get stuck, you don't need snow tires or chains. Clearly a huge savings in money.

(BTW, the above was filled with sarcasm, irony, hyperbole and several other modes of communication.)

[mararmeisto]

(BTW, the above was filled with sarcasm, irony, hyperbole and several other modes of communication.)

Ya, you gave us plenty of ammunition to work with...

OH!

Terrible!

[Blackberry]

Haven't calibrated the speedo with a GPS, but it seems pretty close when I come across those "Your Speed is: "

speed is irrelevant, how accurate is your odometer?

True. I meant that if my speedo reflects my true speed then my odo will reflect the true distance travelled. Bigger tires than the speedo/odo was designed for would result in a slower indicated speed than reality = less indicated distance travelled than reality = poorer indicated fuel economy than reality.

over about a 1500km trip this summer I averaged 30mpg (UK gallons.

That's amazing mileage. The best I've ever seen period.

30 MPG converted to KM/L (L/100KM) is 12.75 KM/L (7.84 L/100KM).

The closest I got to that was 27 MPG and it was an auto, lowroof, all highway doing 90 km/h on flat with no wind and some downhill.

I've owned 2 5-spd's and both got lower mpg than my auto's with the same tires, etc... on the highway.

In the city, the 5spd got better mileage but as soon as you hit over 85 km/hr on the highway in a 5spd, your mileage drops significantly.

I think you must have missed the "UK gallons" part. I should have used the correct "Imperial gallons" term. So 30 miles per Imperial gallon = 9.1 litres/100kms = 10.6 kms/litre.
http://www.tdiclub.com/misc/conversions.html
So if you were talking in terms of US gallons then your 27 MPG best was far better than my result..working out to 32.4 MPG (Imperial)... or 8.7 litres/100km or 11.5 kms/litre. When gallons are mentioned I just naturally think in Imperial 4.55 litre ones since that's what I was raised with here in Canada...and that's the gallon size used in Canada when auto makers advertise in MPG figures here. I agree that I seem to get better economy around town than on the hwy if I'm driving over, say, 90kms/hr. I'd submit that "your mileage drops significantly" at highways speeds applies to both autos and 5spds and is far more attributable to the exponentially-increasing-with-velocity drag than to the 5spds' slightly lower overall gearing.

No takers on why autos come with a considerably larger fuel capacity? I haven't looked closely but could it be that on the 5spds something's in the way so they couldn't fit 2 tanks?

[jessef]

No takers on why autos come with a considerably larger fuel capacity? I haven't looked closely but could it be that on the 5spds something's in the way so they couldn't fit 2 tanks?

Shift linkage is in the way of the 2nd smaller auto tank hence the single tank on 5spd's.

[Green1]

True. I meant that if my speedo reflects my true speed then my odo will reflect the true distance travelled.

Interesting assumption, but rarely the case. From the factory most vehicles speedometers read high, however most odometers are accurate, if your bigger tires have brought your speedometer to accurate, they have likely made your odometer inaccurate.

[Blackberry]

True. I meant that if my speedo reflects my true speed then my odo will reflect the true distance travelled.

Interesting assumption, but rarely the case. From the factory most vehicles speedometers read high, however most odometers are accurate, if your bigger tires have brought your speedometer to accurate, they have likely made your odometer inaccurate.

Uhrg...my brain hurts! Hmm...fascinating! I knew speedos tended to read high but never considered odos would be accurate.
Cool...so then if my speedo is now closer to accurate...and indicating slower than stock ...then my odo will be indicating a shorter distance travelled than reality...so I'm getting even better than the 30mpIg I'd calc'd.

[Green1]

maybe, but not necessarilly, the only way to know for sure is to test the odometer. there are many odometer test sections along the sides of the highways for exactly this purpose.

[Erebus]

maybe, but not necessarilly, the only way to know for sure is to test the odometer. there are many odometer test sections along the sides of the highways for exactly this purpose.

Unfortunately, they aren't really long enough to be useful. In a 5 km section, if you odo shows 1/10th off, which is about as accurate as you can tell, that's a 2% error, but the precision is poor.

What I've done is either by GPS, or find a highway that has kilometre signposts. I did it on the Dempster, where they have a marker every 5 km. Tracked it for 50 km to get a really accurate error.

I noticed recently that in New Hampshire, the Interstate had a sign every .2 mile. Quebec often has every kilometre, and sometimes every 100m.