There is something that may help.

If you push the car remote against your skin, and then press the button, your body will act like a giant antenna to extend the signal. I don’t know how safe this is, but it works.

I first heard about this a few years ago and I was in disbelief, until I tried it. Not only does it work, according to New Scientist, it can almost double the range of your key fob.
When I first heard abou
t it, I was told to push it against my chin. It turns out you can push it again your arms or other body parts too. It relies on a principle called capacitive coupling, the same principle that the capacitors on electronic circuit boards rely on.

This doesn’t work for all types of radio frequency remotes, it works best with relatively low frequency signals with rapidly changing currents, which is what many car remotes use.

You may have heard that the iPhone 4 is having signal issues when the exterior antenna is touched in a certain way and you may be wondering why it has the opposite affect on the iPhone. The difference between the iPhone problem and capacitive coupling is that there is no insulator between the transmitter and your body with the iPhone, but with your car remote, the plastic case acts like an insulator. Again, this is precisely how capacitors on circuit boards work — two conductors are separated by an insulator.