Fuel economy of Xplorers

["Alex Pout" <alpout@optusnet.com.au>]

I've just had a look at Countrylink's website, they reckon a 1700 litre tank
will give an Explorer a 16 000 km range.  Working this out, that comes to
10.625 litres/100km, or 9.4km/litre.  Now, my car (a 97 Barina) just managed
to get about 550km off a 40 litre tank, ie 7.27 litres/100km or
13.75km/litre.  Is Countrylink's claim realistic, or has someone missed a
decimal point?


At first I thought, someone's missed a decimal point, but after thinking
about it for a while (does it help/hinder if I confess to becoming a
mechanical engineer, and done a bit of study on engines?) I thought maybe it
is realistic.  Of course, given time and enough motivation, then I'd do a
basic thermodynamic study (ie train moving at Xkm/h has so much kinetic
energy, engine/drivetrain efficiency probably somewhere around 25-28%, Y
MJ/tonne of diesel etc), but can someone give me a faster answer?

The points I have are: major reduction in rolling resistance for steel
wheel/rail interface compared to rubber/tar for car, but my car weighs about
900kg, the (3 car) Xplorer weighs in at 174 tonnes.  Also, my car has a
smaller frontal area and lower speed (110km/h compared to 145km/h), but it
uses a petrol rather than a diesel engine.  Finally, I know from experience
that most trucks will get from around 5 km/litre for light trucks (small
rigid ones), to around a litre per kilometre for semis and B-doubles, and a
B-double is still only around a 1/3 of the mass of the train.

If this is the efficiency of the train (and extending the situation to
freight), then why doesn't rail freight have so much lower rates than road
that there is no such thing as road transport??

TIA

--
Al Pout

No matter where you go, there you are.

alpout@optusnet.com.au
ICQ 81175245