[RalphVa]

We've both a 2016 3 and a 2013 MX-5, both GTs.

Lost my fob to the 3 and got a new one from Amazon. Far as I can tell, the fobs to both cars are identical. It's just that you cannot use the key in the end of the fob on the keyless 3 ignition button. There's a key in the fob. It's for the glove box, trunk and the doors; I guess.

Hope I have the right key. Plan to take it to a local Lock & Safe place on Wed or Th.

Ralph

 

[hansboomer]

I bought a used key on Ebay recently and a locksmith programmed it with no problem. If you pull the key out of the fob, you can see 7 or 8 lines of numbers. I was able to find a key with all matching numbers except for the top line which I think is unique for each fob. At a minimum, the FCC number, the model number and the number of buttons needs to match.

If it were me, I would try to program all the fobs to both the cars.

 

[RalphVa]

I bought a used key on Ebay recently and a locksmith programmed it with no problem. If you pull the key out of the fob, you can see 7 or 8 lines of numbers. I was able to find a key with all matching numbers except for the top line which I think is unique for each fob. At a minimum, the FCC number, the model number and the number of buttons needs to match.

If it were me, I would try to program all the fobs to both the cars.

I had not thought of that. Will run it by the wife and see what she thinks.

Ralph

 

[RalphVa]

Had the new and old fobs and car reprogrammed at a local place. Twas a little more difficult than normal. Ended up costing $100.

Didn't do the MX-5 fob the same. They both have keys (for glove box, doors and trunk on the 3, and for ignition on the MX-5). Would have had to change the locks on all the stuff that took the key to have them the same.

The wife pinned both fobs inside my fanny pack to avoid dragging them out by mistake which apparently is what happened to my original fob for the 3.

Ralph

 

[hansboomer]

Didn't do the MX-5 fob the same. They both have keys (for glove box, doors and trunk on the 3, and for ignition on the MX-5). Would have had to change the locks on all the stuff that took the key to have them the same.

Could you have programmed the transponders the same? That way you would have only one fob and you could carry a simple flat key or hide it on the outside of the car.
FWIW I carry my fob in my wallet with one of these, so the one fob solution is way better for me:
https://mx5things.com/2017/10/28/car-key-in-the-shape-of-a-credit-card/

 

[RalphVa]

I wear a fanny pack every time I go out. Both fobs just stay inside it. Have a spare 3rd key for the Tacoma in there, too.

Ralph