I think the break even point as to CO2 is around 100K miles. I imagine most vehicles are driven far beyond that. As the numbers show 10-20% reduction. That is not nothing or trivial. But EV's are being marketed and most buying them are buying into a "CO2 free" notion. Of course, when is marketing really honest?
Anybody who tells you a general "break even" point at XXXX miles is either generalizing to make a point or doesn't know what they're talking about. You can of course estimate it, and people have tried, but there is no standard break even point for EVs in general, or even within the same models. It depends on factors unique to each EV during it's manufacturing and then usage. What is the battery chemistry? Where are those materials sourced from? How large is the battery? How clean is the energy used in production and then charging in customer hands? Does the owner commute efficiently with it, or are they ripping 0-60 pulls or towing all the time?
MIT says that the same 82kwh battery in a Model 3 could have a footprint that ranges from 2.5 tons to 16 tons of carbon depending on the answers to those questions:
It depends exactly where and how the battery is made—but when it comes to clean technologies like electric cars and solar power, even the dirtiest batteries emit less CO2 than using no battery at all.
climate.mit.edu
There are also efficient EVs and inefficient EVs just like there are efficient and inefficient ICEs. Edmunds has tested a bunch of EVs for range with fairly standard practices. In the real world, a new Lightning with the Extended range battery and a Tesla Model 3 Long Range both get 345 miles per full charge:
Which EVs have the best electric car range? The EPA provides range estimates for every electric vehicle, but they don't test EV range in the real world -- and Edmunds does. Read all the latest real-world EV test results from the Edmunds experts.
www.edmunds.com
But the Model 3 does it with an 82 kwh battery pack, while the Lightning does it with a 131kwh battery pack. The new Hummer EV gets around 310 miles, but uses a massive 200kwh battery. So, not only do the larger, heavier, less aerodynamic EVs have much larger footprints during manufacturing, but they also guzzle more electrons per mile too. So if you're comparing footprints of say an ICE Civic vs an EV Hummer, the Hummer may never break even. But if you're trying to do an apples-to-apples comparison of an ICE F150 and an EV F150, then the EV likely pays off fairly early in it's life, even if it's charged on coal. If we're being honest, a PHEV option (if it existed) would break even sooner than the full EV because you'd get more EV miles driven per kwh of battery capacity, but that's not currently an option.
If you want, you can play around with footprint estimates using the same tool the .gov does here: