The phrase "There are lies, damned lies, and statistics" is attributed to Mark Twain. The Teslanomics pages of the TeslaRumors website are dedicated to cost comparisons of the Model S to just about everything else. It all sounds great, but then I looked over the comparisons of the Leaf to the Model S:
Looking at the numbers, depreciation is the biggest factor. So, while Model S costs $20K more than the Leaf to buy, when sold after 5 years, Model S ends up only costing $10K more. Note that the math doesn't quite add up on the Teslanomics pages, and that the depreciation they calculate for Model S is different on the Porsche page than on the Nissan page, for instance. On the Porsche page, they calculate depreciation as 50% of the tax-rebated price, for instance.
Model S - 160 mile - $7500 Credit Leaf SL Electric - $7500 Credit
MSRP $57,400 $37,250
Fuel $2,025 $3,777
Depreciation $33,292 $21,966
Maint $3,000 $2,708
Repair $1,000 $773
Total: $31,817 $21,724
But, is a 50% residual really the right number? According to this analysis of Edmunds.com, the best cars retain 54% of their value after 5 years, the worst only 20%. Is it right to predict EVs residual values to be at the top end, especially considering battery replacement concerns? And even then, this ignores the time value of money.
I think there's no way to tell what actual depreciation of electric cars will be. The TeslaRumors comparisons to Prius and Rav-4 EVs are not applicable in my opinion. RAV-4 EVs are special, limited, and have been highly sought after by people wanting EVs. But, with the increased availability of the Leaf and the upcoming Tesla-powered RAV-4 EV, I predict their value will drop pretty quickly. Used Priuses are sold like regular cars getting good MPGs, but only because it's been over 10 years and people have seen that they didn't have to replace the battery at 7 years or 100K miles, as was widely predicted when the car was first introduced. Today, everyone is today worried about Li-Ion battery replacement costs, and that's going to put a huge damper on EV resale until such time as people see for themselves what replacements are/are not needed and the cost. Granted, Model S's 8 year warranty will help preserve some resale value, but maybe mostly on the 85K version with unlimited miles.
And, while it's hard to ignore the depreciation elephant in the room, is maintenance on the Model S really only 10% higher than the Leaf? Is the Model S more efficient, resulting in lower fueling costs?
I believe the Model S will turn out to be a cost effective way to drive compared to roughly equivalent ICE cars, and that electric drive has many other non-cost-related tangible benefits, but I don't believe what Teslanomics (not affliated with Tesla, btw) has the right cost analysis. I think one has to look at the spectrum of depreciation possibilities for Model S and then determine via one's own crystal ball at which end of that spectrum Model S will end up at. In that regard, the few thousand more expensive Signature series might end up costing less, since it might be worth more at resale time to collectors.