1/ Now, I'm sure you don't want to do this, but I found it in the review section of Amazon.com:

RANGE! Range is horrible. The transmitter is powered by only two AA batteries. I originally got under 20 ft without a modification I describe below.

TRANSMITTER MODIFICATION FOR ADDITIONAL RANGE

This simple mod involves replacing the 2xAA batteries with a standard 9Volt battery.
This will void your warranty and you do it at your own risk.
I am able to get over 80ft with this car now by juicing the transmitter up to 9 volts. Here's how:
(1) Remove all the screws from the back of the transmitter.
(2) Pull the rear cover apart.
(3) Pull out the existing AA batter holder and CUT both the red and black wire to remove it.
(4) Solder or wrap a 9V battery connector (the "hat") to the cut wires. You can go to radioshack or cut them off some old electronic item you have.
(5) Put the hole thing back together (don't put the old AA battery holder back in).
(6) Insert new 9V battery. The battery cover will stay in as long as a 9V battery is installed; you'll see what I mean.
(7) You now have double the range!!!!!

Me again....I suppose you could temporarily connect a 9 VDC battery to the AA connections with some alligator clip test leads to see if it helps.

AND, only 2 AAs in the TX? Wouldn't take much of a voltage loss there to screw things up, so don't use NiMh or NiCds. Go with Eneregizer or Duracell.

2/ Typically, if everyting else checks out, the Transmitter and Reciever may not be aligned to "exactly" the same frequency. Also, the Tramsmitter output may not be maximized. Unfortunately, these are not things easily accomplished at home. Nor do I have the particular radio system, so I can't give specific details. Basically, it appears you may have to send them back.

If you know a friend who dabbles in electronics, he can tweak the frquencies by adjusting the receiver front end (potentiometer, NOT a tuning coil). Without test equipment, you move the vehicle back until the transmitter stops controlling the vehicle, and then make a slight tuning adj until it starts operating again. Keep moving back and repeating until max range is obtained. For the transmitter, they quite often de-tune the output crcuitry to the antenna. Typically, a slight adjustment of the second tuning coil back from the antenna (and you really need an oscilliscope for this, although you can do the "moving away" trick) can maximize output power to the antenna.

I suspect the day your two vehicles were made, someone didn't do the radio alignment correctly. So, I recommend sending them back. It's a pain, but there are lots of other "cool" RC stuff to pick from. A last ditch effort may be to call Tyco. Maybe you'll get lucky and they'll send you two new ones with no questions asked.