Playing With the Numbers

Keeping a log of all my runs in the two trucking projects gives an opportunity to compare the efficiency of the two trucks that we ran in parallel.    This is not a straight forward task for a number of reasons which I will discuss.  The conclusion I reach will of necessity be clouded by a number of intangibles.   But let’s start with the trucks themselves for they are in some ways chalk and cheese.

Our Volvo FH has a 4×2 chassis while the Kenworth K100 is a 6×4 – both are seen as standard configurations for tractor units in their home European and US truck markets.   A 6×4 chassis is commonly believed to have a small negative effect on fuel efficiency.   The K100 is also quite angular in appearance whilst the Volvo FH is more aerodynamic.

The engines are closely matched power wise at 450HP for Detroit Diesel in the K100 and 460HP for the Volvo D13K and their swept volumes are quite close – 12.1 and 12.9 litres respectively.   But there the big differences kick in.  The Detroit offering is a V8 two-stroke while the D13K is a 6 cylinder in-line four-stroke engine.   The Detroit engine dates to 1974 and was a very widely used in trucks and buses throughout the 1980’s in the US.   Production ceased in 1995.  The D13K entered production in 2012 and is to the latest Euro 6 specification which is aimed at reducing emissions.  One would think that reducing emissions ought to have a positive effect on fuel consumption but whether that is actually the case is a matter for debate in other forums than my blog.

Having set the scene, let’s move to the numbers for the trucks…

Volvo FH                              19 trips                 14.74 tonnes      29.63 l/100km    7.94 mpg

Kenworth K100                  10 trips                 13 tonnes            30.43 l/100km    7.73 mpg

…which seem to bear out the assumption that the modern truck with the latest engine should be more fuel efficient.   It doesn’t appear to be by a lot though – 0.21 of a gallon per mile.   But that’s with a 1.74t weight penalty.   I looked at ways to even out the weights to get a clearer impression of the difference.   If I take the runs done by our Kenny for the Doubles Event where the tonnages were all in the high teens and select similar weights from our European deliveries we get a clearer picture…

Volvo FH                              9 trips                    17.67 tonnes      31.18 l/100km    7.54 mpg

Kenworth K100                 10 trips                   17.5 tonnes        35.05 l/100km    6.71 mpg

…with the K100 clearly burning significantly more fuel than the Volvo.   It equates to 16.4 gallons difference every 1000 miles – that’s around a $52 saving for the modern truck compared with the old stager using the October 2017 cost of diesel in California.   Small margins on a single truck become massive savings on a big fleet!

This is not a rolling road test where all factors are the same.   I suspect that the real world margin is even higher but the only way I could test that would be to put the two trucks into the same environment and haul the exact same loads with them.   Even then the results could be skewed by the traffic on any given run.   The general driving in Euro Truck is much more varied than in ATS.   Most of the driving with the Kenworth has involved long stretches on the interstate with cruise control on at around 55mph.   In France you either have back roads with lots of roundabouts or autoroutes with regular stops at tolls to break up the cruising.   In Germany you have no tolls but lower speed limits on the autobahnen and back roads.   There are similar road challenge issues throughout Europe.

An interesting illustration of the point is the run from Linköping to Oslo which was one of the runs included in both sets of figures but critically it was included in the second set of figures to even out the weights hauled and could be viewed as having an impact on the FH’s overall results.   This was the lowest weight at 15t but because of the nature of the roads and some of the gradients encountered along with slow moving traffic it was actually the Volvo’s worst for fuel consumption in the subset at 6.82 mpg.   The only similar road encountered by the K100 in our sequence of tests was the run from Redding to Eureka with 17t where the fuel consumption was 5.86 mpg.

The overall conclusion is that the ETS2 / ATS games do provide a good representation of the real world fuel consumption by the trucks (assuming you’ve turned on realistic fuel consumption in the game settings!).   I would expect the modern truck engine to be more fuel efficient than a 40 year old design.   The amount of difference is partially obscured by the differences in the ETS2 / ATS road environments.   What is not taken into account is the relative maintenance costs and for a real world self-employed trucker these might swing the balance when choosing to stick with a less complicated older engine.   You can find lots of videos on YouTube exploring this.

One final real world difference between the US and Europe that I want to mention.   In Europe you buy a Volvo, you get a Volvo engine.   A Mercedes-Benz – you get one of their engines.   In the US it seems that whilst certain trucks are allied to certain engines – Freightliner with Detroit Diesel and Kenworth with PACCAR  – a buyer can order what is known as a ‘glider kit’ if they want which is the truck without an engine or drive train.   They can then specify whatever make of engine / drive train they want.   So you find Kenworth trucks with Cummins or Caterpillar engines in place of the PACCAR units that would be the factory standard – or in our case a Series 92 Dee-Dee.   It’s a different market!

This was an interesting mathematical experiment for me.  I wanted to see whether the modern truck is more fuel efficient and I think that has been borne out by the figures.   It’s been a good way of keeping the grey matter active which is a healthy thing to do.   I’ve also done a lot of research into the real trucking world over the months of playing ETS2 and ATS.   These truck sim’s may be ‘only a game’ but the opportunities for straining the brain are there if you want to take them 🙂

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