It doesn't matter. For your car, for the battery state in your FOB, for interfering obstacles, the range found is for those conditions.
<JOKE>
I for one am sick of seeing Amateur Radio Service spectrum being gobbled up for the sake of lazy schnooks who are too lazy to walk up to a car, stick a key in it, and turn it. I mean, hell, you're walking toward the car anyhow.
</JOKE>
In addition, I needed two extra keys for my venerable old car, walked into the dealer, showed them the registration, and they cut two keys for me for USD$8.00 American Money per key.
That was 'murrikin money, mind you.
And the batteries in those keys never run down for some very sophisticated technical reasons.
And if the car battery goes dead, I can still get in the car, also for some very sophisticated technical reasons.
I'm not signing this one so nobody will know who posted it.