FM Reception -Car Antenna vs. Home Antenna

I live in a hilly Northern California city. My reception on my home stereo is bad & I've tried several different home antenna's. I use a Mcintosh Tuner, so the tuner should not be the issue here.
Why is it that my reception is pretty darn good in all of my cars right outside of my house?
Why not just buy a car antenna & hook it up to my home system?
Sounds like a pretty stupid question, but what's the deal?
Thanks in advance for your time.
What do you mean when you say home antenna? Those small table top size amplified antennas are a joke. The little T Wire works as well.

I have a large roof antenna in my attic crawl space, and can pick up FM stations clearly 100 miles away.

Good car stereos have a really good FM. As a matter of fact Creek uses a car stereo FM chipset in his tuners. The Cambridge Audio T500 tuner has the same car audio chip.

What Mac Tuner so you have?
I have one of those 4 ft. monster poles that plug into an ac outlet. I've put it out in the garage on the ceiling.

My Mcintsh is the MR85.
For the price of this tuner, you'd expect better reception than your car. Or at least I do.
A lot of people do have reception problems in my area.
Great FM reception is based on location of the antenna with relationship to the radio stations FM transmitter. The best FM spot in your house may be where you least expect it.

Here's a simple experiment. Take a portable radio and tune it to your favorite radio station. Now walk around your room and listen to the audio quality of the signal as you move from location to location. The area that you get the best sound and highest signal output is where you should locate you indoor antenna.

If you are planning to install a roof mounted antenna make sure your installer uses a field strength meter and aligns the antenna with the transmitter of you favorite radio stations.
Try a Magnum Dynalab whip antenna. It is essentially the same as a car antenna. I have also had luck with Godar Model 1:
The real solution is to install a rooftop, but that does not work for most.
Modern car tuners are much better than home audio tuners but your Mac should be a good one. A car antenna does not work well at home because car antennae use the car as part of the antenna. A rooftop antenna is the best and one with a rotor is even better. You should get the largest antenna you can stand and as a side benefit it could bring in TV as well and HI-Def if you are interested. A hilly area is murder on FM reception unless you live on the hill or in the right place.