Fuel consumption

Wouldn't your GPS reading be "as the crow flies"? i.e. line-of-sight distance between two waypoints, and useless for fuel consumption calcs?

Hi Gang,

Don't think that your GPS necessarily gives an exact measure of the distance you travel. Your GPS calculates the distance between the fixes it obtains and it assumes that you have travelled a straight line between these two points. If you are travelling around a curve the GPS actually measures this as a number of straight lines connecting points on the actual path.

Now if the GPS is getting a good fix every 1 second or so the inaccuracy around a curve may only be about 0.3%, however if there are trees around or you have the antenna located such that it needs to change satellites rounding a curve then the under-reading can be quite significant.

If say, you drive around a right angle curve at 110 kph with a radius of 200 metres, a fix every 1.5 seconds will only give an error of about 1 metre. If the GPS gets a fix every seven seconds (about the time it takes to round the curve) then the error will be more than 30 metres, over a distance of about 315 metres.

Over a lengthy drive you should expect your GPS to give a distance reading that is less than the actual distance travelled.

Cheers Frank.

Around town i get about 14 when i'm being nice on the highway i can get it high 11's but usualy about 13. i've found the consumption not to change between my 94 and 2000 models, both non turbo's, 2000 has a factory snorkel.

As for your speedo, the 31' tyres are smaller than the standard splits. this causes the wheels to spin faster.

Mine both have standard diameter tyres but i'm a little surprised that this hardly affected the consumption.