My ZZMT remote was giving me between 10' and 15' range, so here is what I did.
I took 1' of cat5e 350Mhz Media Twist wire (solid wire with bonded pairs). Each pair of the wires is bonded and twisted at a specific rate to increase throughput (think Gigabit Ethernet).
I took one set of the bonded pair and stripped a 1/4" bare end and soldered both wires to the antenna connector on the PCB of the MT.
The second 1' pair I stripped 2" at each end of the wire and wrapped the top of the TX and the bottom of the TX antenna, creating a loop.
Now, Indoor I got 50' range (ran out of house

) and Outside I got 100' range before I hit a bump and tipped over. This weekend I'll take it to the church parking lot where I will have a flat surface of over 100' to see if it will go farther.
With that kind of range... you are really looking for the antenna that sticks up rather than the tiny speck of the car itself.
Obviously this is a definite take off of others ideas, thanks to those that posted these ideas! I just wanted to post my results in hope that it will help others get their range increased as well.
If you wanted to try the same wire, you should be able to buy it at Lowes or Home Depot by the foot. I suggest you get the solid and bonded pairs. It is supposed to be the best Ethernet throughput and when bent will hold its shape.