There appears to be no meaningful discussions or data on the life of the battery in the hybrids and the cost of replacing them. At a recent car show the Mercedes rep estimated a life of 100,000 miles an a current replacement cost of $10,000. Cadilac was slightly less as to both life and cost. Except for this small bit of information nothing additional has been provided on similar inquiries and nothing has been provided in all the recent articles regading this issue.
100k is VERY low, many many Priuses are seeing much more than 100k. What car are you wondering about, in particular?
It’s not being discussed much because very few hybrids have neede a battery replacement, despite some very high mileage.
I’m sure this will become an issue a some time in the future, but until battery replacement starts to become common there’s not much attention being paid to it.
“At a recent car show the Mercedes rep estimated a life of 100,000 miles an a current replacement cost of $10,000. Cadilac was slightly less as to both life and cost.”
If they’re that low…then consider the Honda or Toyota hybrids…
Not bashing either of those vehicles…I don’t think that’s right…I have over 170k miles on my regular 12v battery…and the hybrid batteries are designed to last much much longer then the standard 12v batteries.
The way the batteries are designed they can be serviced. The batteries are really a series of smaller batteries. Companies have already sprung up to service these batteries. They just replace the bad cells at a much cheaper cost.
Maybe the MB and Caddy guys were telling the OP the warranty coverage. 100k or under is a non-starter (sorry!) for expected life.
I have a 2007 and 2009 Prius. My battery in the '07 died at 165K miles. The cost to replace is $4K by Toyota (didn’t I buy this car to SAVE me money). So, it sits in my garage waiting for me to pull the new tires, etc, and place on my other Prius that hopefully still has 65K mile left on it before it too hits the short end of it’s Hybrid lifecycle. Toyota would not replace the battery at their cost (probably $2K max with me offering to pay the labor) and therefore lost a family of once extremely loyal customers that had already spent over $70k. Wow, to walk away from a loyal customer for $2K – Toyota must be doing extremely well! So goes the ole adage, “Fool me once, shame on you. Fool me twice, shame on me.” Oh, I have found that KIA is accepting new loyal customers 
Have you checked for companies that rebuild the batteries for less?
A friend had a new '06 Honda Civic hybrid. Initially the mpg was about the 50 mpg expected. After a few years the mpg dropped off into the 30’s for the same type of driving. The battery had deteriorated. It wasn’t providing full power to the electric motor putting more work on the gas motor and also using more power from the gas motor to recharge the battery. He turned it in and bought an '09 conventional civic and is very satisfied to be back with a conventional drive train.
I think what happened is he used the Civic hybrid primarily for highway driving. Not the best set up for maximizing a hybrid and perhaps shortened the battery life in his case. Any predictions of battery life are just guesses. The type of driving and other factors aren’t taken into an account and the fact is noone really knows. The hybrid batteries last until they are shot. Starting batteries in conventional cars are much the same, they last as long as they last; for some that’s 2-3 years and others are still going after 10 years.
You want data?
Idaho National Labs has thorough tests on hybrid vehicles. In 2006, they produced a report about the longevity of batteries on first hybrids. Specifically, at 160,000 miles, they tested battery capacity and mpg for Insights, Civics, and Priuses. They found considerable dropoffs in battery capacity of 14-60%, depending on model, but very little change in actual measured (via SAE methods) mpg. The bigger change seemed to be the onboard computers were going way off of actual mpg, saying the cars were getting significantly better mileage than they were.
Read it for yourself here:
As for cost, Mercedes and Cadillac would be the absolute wrong places to go to ask for cost. They have very limited experience with hybrids and they’re luxury brands that will overcharge for everything. If you look at Toyota’s prices for a Prius battery, you’ll see that their MSRP is $2,729.35 , but you can get it cheaper. There’s no way there’s $7,300 in labor involved (or anything close to it), plus the dealer gets a nice hunk of cash from Toyota for your used battery, too…
The current generation of Civic hybrid is a severe outlier. Honda has had problems with the battery packs and they’ve actually reprogrammed cars to extend the battery life rather than fix the batteries (cheaper that way), and that’s led to a dropoff in mileage. It isn’t just your friend - there are class action lawsuits against Honda for it by owners that aren’t getting anywhere near EPA estimated mpg… or even any better than a conventionally powered compact.
just one more reason to avoid hybrids altogether.