The Reason is simple - everyone experiences the same 24 hours in a day - No more - no less, and the planet spins us once for that 24 hours. In this - we are all equal - not counting those the are among the days dearly departed.
Also - in terms of cleaning up the atmosphere - the planet could care less how much you drive - but it might notice how much fuel you burn! Hence - L/Day.
So - what is an obtainable Figure in terms of L/Day? For that - let's consider 4 examples: Someone who walks to work, but drives the kids 5 Kms to their after school games, just 3 X a Week; A Short Distance Commuter covering just 10 Kms per day; a Mid distance commuter who drives 60 Km Per day, and a Long Distance Commuter that drives 190 Kms per day (IE: Barrie - Toronto - Return).
If the Drivers each have the same vehicle - that delivers 9.0 L/100 Kms average Fuel Burn, what would be the effect of switching to a Vehicle with a 5.0 L/100 Km Average Fuel Burn?
Let's put those numbers into easier forms to work with:
9.0 L/100 Km = 0.09 L/Km; and
5.0 L/100 Km = 0.05 L/Km.
Our Walker - would use no fuel for the commute, and for driving 5 Kms for three times in the week - with the first vehicle - would burn 15 x 0.09 Litres of Fuel = 1.35 Litres Per 5 day Week, or an average per day usage of 0.27 L/Day. With the second vehicle - the numbers would become 0.75 Litres per 5 Day Week, for a daily average of 0.15 L/Day. That is about half, and about what we would expect given the two selections.
Our Short distance Commuter who drives 10 Kms per day - or 50 Kms per week, would use - in the first vehicle 4.5 Litres Fuel per week, or 0.9 L/Day. With the Second Vehicle - the numbers would be 2.5 Litres per week, and 0.5 L/Day.
Our Mid Distance Commuter - driving 60 Kms per day or 300 Kms per week, would with the first vehicle use 27 Litres Fuel for the Week, or 5.4 L/Day. Changing to the Second Vehicle - The Consumption would drop to 15 Litres per week, and that equals 3.0 L/Day.
Our Long Distance Commuter Example above - driving 95.0 Kms each way to work, and back, for 190 Kms per day, when using the first vehicle, would consume 85.5 Litres of Fuel for the week, or just 17.1 L/Day. If they switched to the More economical 5.0 L/100 Km Vehicle - they would still use 47.5 Litres fuel per week, or 9.5 L/Day.
Example Vehicle 1 @ 9.0 L/100 Kms Vehicle 2 @ 5.0 L/100 KmsWalker + Games 0.27 L/Day 0.15 L/Day
Short Commuter 0.9 L/Day 0.5 L/Day
Mid commuter 5.4 L/Day 3.0 L/Day
Long Range Commuter 17.1 L/Day 9.5 L/Day
From this quick tally - it can be seen that the Long Range Commuter, even if switching to a vehicle nearly twice as fuel efficient, because of his driving distance - will still burn More Fuel than someone 1/3rd the commuting distance, but with a vehicle with about half the efficiency,
For the Long Distance Commuter to get his Daily Fuel Burn down even to the level of the mid Commuter's worse level, they would have to switch to a vehicle with an efficiency of 2.84 L/100 Km, then it could net a daily consumption of just 0.0284 x 190 = 5.396 L/Day.
To get Anywhere near that low fuel burn - as an average - it would take finding a vehicle with a fuel burn that is one-third as thirsty, and mostly today - that would reach into the territory of Plug-In Hybrids like the Toyota Prius PHV, and the Equivalency Ratings of Electric Vehicles! (MPGe)
Three Things are evident in this quick comparison:
1) Carpooling would increase the Effective, or 'Per Person', or 'Seat Miles Per Gallon' type of efficiency;
2) Moving closer to work is a great way to burn less fuel per day; and
3) Walking to Work is the least fuel dependent (but generally requires a much closer distance to work)
So depending on the options or desires to Move Closer to work so as to Reduce the Commute, the alternatives come down to switching a vehicle (or two - depending on each vehicles usage cycle) - to a more fuel efficient vehicle.
If the bottom line is fuel consumption improvements - not just cost, the lowest fuel burning vehicle is the one that burns no fuel - an All Electric Vehicle! Next to that - and from this example - for all but the longest range commuter - there are choices of Plug-in Hybrid Vehicles that offer between about 20 Kms, and those that offer 43 Kms, or even over 55 Kms of All Electric Range*1.
*1. All Electric Range (AER), a Term used in Plug-in Hybrids to define how far they will go before the Electric Only mode is supplanted by the starting of the Engine (Typically Gas, but Diesels are Coming) to generate Electricity or Power to keep moving.
Other Related Stories:
Plug-in hybrid Prius a money saver for urban drivers
Alternative Fuels Data Center - Plug-In Hybrid Electric Vehicles
2012 Toyota Prius PHV Plug-in Hybrid
Ford Fusion Energi (Quietly) Rated at 21 Miles Electric, 43 MPG Extended (21 Miles = ~33 Kms)
Ford Fusion Energy - Wikipedia
Fusion plugs into new motivation
Long drive proves Volt works
First Look: 2012 Chevrolet Volt
Further conversations on this thought will discuss the MPGe or L/100e figures of All Electric of Battery Electric Vehicles with no other Engine or propulsion system, in Future Posts.
I Walked to work today - Instead of Driving my Prius!