Can you add a motion sensor alarm to your 2001 Chrysler Sebring lxi without interfering with its factory installed alarm system?

No you should not - all you need to do is make sure you have comprehensive insurance. Comprehensive insurance from a major insurance company includes THEFT.

Because the motion sensor is an aftermarket product it will void you from a warrany claim with your insurance.

I have owned 4 motorcycles and 2 cars all in NYC - I never lock my bikes, I just make sure Im covered for theft. 3 Bikes have been stolen and insurance has cut me a check with in a week each time. Insurance will not pay for aftermarket products, like my saddle bags and screamin eagle pipes unless it is named in your policy.

So basically motion dectectors do nothing other than annoy your neighbors and make you look like a guy who cares way too much about his car.

Take my advise and bulk up on insurance and then park where ever you want.

Hope this helps