My 2007 Prius has 128,580 mi. HV batt warranty was 7 yrs/100,000mi (not CA.) I average about 46mpg. The cost of replacing the batt was $3100. at dealership. Miles driven were ~70% hwy miles. OK, lets figure this out with a little help from an Excel spreadsheet. I won't bore u with the details, but @ $3.50/gal for gas, if I had another car that gave me 35mpg my total cost would be the same. The cheapest batt with self install is about $1200. An equivalent cost would get me a 41mpg car. IF U were to get 200,000 miles out of a batt, then the equivalent mpg would be 38. At CA gas prices of $4.50/gal and 150,000mi (out of warranty) the equivalent is 39mpg. None of this factors in any additional purchase cost. Do u feel lucky??? Does this prove u can't beat the laws of physics??? energy in = energy out, and somehow ppl have figured out how to make it all equal. Read more: http://priuschat.com/conversations/add#ixzz2NU7JgNHE
Yes, simplest way is to balance fuel + battery against fuel g/P + b/m = g/O => 1/P + b/mg = 1/O => O = 1/(1/P+b/mg) Where O = other car mpg, g $/gal, P is Prius mpg, b cost of the battery, m is miles battery life. I'm in a CARB 10/150k state currently and last time filled up with $3.709 gas. I drive more than 15k miles per year. Let's say 50mpg (I actually get 52mpg with a bit of hypermiling) Assume $3.5k OEM battery replacement. Then O = 1/(1/P+b/mg) = 1/(1/50+3500/(150000*3.709)) = 38.03 We weren't getting 38mpg average in our Civic, although I did get a couple of 44mpg tanks in spring commutes in the Civic. But then, I could beat 50mpg in the Prius too. Plugging in 41mpg for a Camry Hybrid and you get 32.59mpg. As you identified, the key is low battery cost per mile, which is why the 10/150k warranty is so helpful and why I wouldn't recommend a Prius to a low-mileage driver.
