Since I first came to riding as transportation, I have heard the argument that motorcycles/scooters are NOT more cost effective than cars. To a certain degree, I have been willing to take that at face value. In my mind, it has always been a bit of a wash between the fuel savings and other costs, but there really isn't a way to really gauge the real difference.
The reason is that there are no metrics that makes sense when comparing cars to motorcycles. Miles Per Gallon and MSRP are the most often used metrics, but these are worthless numbers really.
Cost Per Mile
This is a metric I can get behind and work with, but what is a cost per mile? In order to figure out a real cost per mile, you need to address the myriad of costs, not just gas mileage into account. In order to give a reasonable expectation of getting a usable and consistant output number, you have to have some baselines for the metrics. The first is to decide how long the Cost Per Mile is calculated, the second is to establish baselines for average fuel costs.
For the purposes of my metrics, I went and found the US Governments listing of average gas prices over the last 18 months to get a number 2.68. For the electric vehicle I included, I used the vendor supplied estimate of .18 per charge and inflated it by 30% to .24. Next, I selected a term. Since 3 and 6 years seem to be pretty natural trade/replacement points in vehicle lifecycles, I used 3 and 6 years. The last baseline required was to establish a # of Miles Per Year guideline. I cheated here and looked at standard lease values. Normal and High are lease milages. Low is a number that seems to be about average for the recreational riding community. So we have Low, Normal and High at 6000, 12500, and 25000 miles per year.
First we have the MSRP, the purchase price of the vehicle. This cost is fixed, regardless of the miles driven so it has to be split out over the time of ownership,
Next we have the regular maintenance cycle, with oil changes. These have factory intervals, and a cost. Factor in tire change intervals and cost (seperate for front and rear), expected major service interval and cost, est fuel milage. Because insurance costs vary so widely by driver and zip code, I would like to include this number, but cannot find reasonable statistics to do so with.
Taking this approach, I can arrive at a base cost per mile using the formula:
Cost / Interval for each expense item + Fuel Milage / Cost of Fuel Unit.
From there I have a number I can extrapolate out from. Adding in a cost of additional gear and services to each vehicle for each year of ownership and adding in the MSRP / number of years to the miles driven * the base cost per mile, I get an estimated Cost Per Mile for each vehicle.
I started with my BV500. With it's service intervals, I get a Base Cost Per Mile of about $0.15. This is for all intents and purposes the 'operating cost'. Add in the $6299 MSRP and a $500 / year budget for gear and service above the expected services for 3 years, and you get a 3 year cost per milage numbers of $0.75 @ 6000, $0.44 @ 12500 and $0.29 @ 25000.
What this tells us right away is that the more you use the vehicle the better the cost per mile gets.
So what about my wife's SUV? With it's service intervals, it has a Base Cost Per Mile of $0.24. When you factor in the MSRP of 42000, it has 3 year cost per mile numbers or $2.57 @ 6000, $1.36 @ 12500 and $0.80 at 25000. Since most families keep this type of vehicle longer, if you use a 6 year number, you get $1.40, $0.80 and $0.52.
Seeing those numbers, my curiosity got the best of me. Our SMART forTwo works out to a 3Y Cost Per Mile of $1.16, $0.62, $0.37 and a 6Y Cost Per Mile of $0.64, $0.37, $0.25. A hypothetical used suburban for $5000 early 90's by KBB pricing with a 1000 / year of older car service budgeted in does better in the short term than it does in the long with a 3Y $1.07,$0.67, $0.48 and a 6Y of $1.43, $0.84 and $0.57.
Yes, there is a lot to process here, but what you can take away from it is that motorcycles actually do hold up well in terms of value, and they only get better the more miles that you use them instead of a car. But what about WITH a car?
Let's say you are a high mile person in your car, and you replace a portion of those miles with a scooter, does it still make sense? If your car is a SMART, no, it isn't even close. However, if you use a scooter enough to cut 10000 miles from your SUV's usage, the numbers start to get really close.=, especially if you talking about a smaller displacement scooter like a Genuine Buddy 150.
But where it gets really interesting is with the Vectrix. Despite it's high purchase price, the lack of regular oil changes gives it a a base cost per mile of just $0.06. It gets the same 3Y and 6Y scores or $0.81, $0.42 and $0.24. Given those numbers, it really is not out of the price line, nor is it as impractical as it might appear. The downside, is that due to it's limited range, it is almost guaranteed to be in the low side of the equation.
The harsh reality is that the math actually bears out that a scooter (or motorcycle) is a less expensive alternative to most cars as a replacement, but not as a supplement.
You can see the spreadsheet here.