I bought a this cartridge-style block heater which lists it as compatible with my 11th generation 2015 Corolla. However I cannot see the insertion slot that is visible in this video for the 10th generation Corolla (and also in this one) without taking out the air filter and I don't have the correct socket wrench to do that myself.
Half of the dealers I have called said the 2015 supports the block heater and half say it does not (without explaining why or why not). This site says it is compatible. Amazon does not list it as compatible.
I can't find any reference in Google that mentions a block-heater actually being installed in a 11th gen (2015-2016) Corolla.
I only have a few more days to return the block heater and I would like to know if I will be able to install it.