Does anyone use a key keeper (small magnetic box)?
Which one is big enough for the es key and where on the car is the best place to attach?

 

Any key keeper device I have seen will only hold a conventional mechanical key.
The ES keyless fob does have a removable mechanical key which will open the
drivers door but will not then start the car. Why do you want to secure a key on
the outside of the car?
1) Do you want to run, swim, kayak or other activities that the heavy fob would
interfere with? The fob of 2013 and newer ES's can be "turned off" by holding
down the "lock" button and pressing the "unlock" button twice. Watch the small
red fob light and it will flash four (4) times. Slip the mechanical key out of the fob
and hide the fob inside the car. Press the inside door handle lock button and leave.
When you return use the metal key in the driver's door cylinder, recover the fob
and press any button to wake it up. Get in and Go!
2) Do you just want to get in if you misplace your regular key fob? Do all of #1
above and try putting the magnetic key keeper with just the metal key under the
back edge of the hood. Be sure to pick a spot that the wipers will not contact.
As long as the fob hidden inside the car is "turned off" you will be able to use
the regular fob normally, keyless lock, unlock and start stop.

 

i want to find an easiest solution to be able to get in the car and drive in case of a lost key and fob

 

The Remote app will lock/unlock the car from a smartphone. That would be my recommendation in lieu of a hidden key.

 

isn't this a paid feature via enform?
also this will not help start the car

 

Yes, that is an Enform feature so there is a fee. It will lock, unlock, locate and/or start the car.

 

Enform will start the car from the app, but won’t let you open the door without shutting the engine off, let alone drive the car.

You’re going to have to accept that in a modern car with a smart key access system this kind of “hide a key” thing isn’t going to work without a lot of risk.

If if you really want to put a $300 smart key in a cheap magnetic key holder and put it under the car, issue is anybody can unlock your car, because the key is there and when they touch the door handle closest to that keys location, it will likely unlock. You could turn the key off as mcomer described and do this, but you still risk losing or ruuining a $300 smart key.

Only way way to achieve this without risk is to put a smart key in the car, turn it off as mcomer described or take the battery out and have that in there for you to access and reinstall he battery after unlocking the car with the app. Yes you will need a subscription past the trial.