Garage smoke and motion detectors?

Hello,
I am putting together a purchase order for a DSC PowerSeries Neo system. This system supports both hard-wired and their PowerG Wireless detectors. It is an existing house so I’m hoping to mostly use wireless, and I am considering how to best protect the attached garage from intrusion and fire.
In my current house, in a municipality far far away, we could only install a heat detector in the garage, not a smoke. I was told that this was code to prevent false alarms. The DSC PowerG Wireless products do not include a heat-only detector, so for that I’d need to run wire.

What is the general wisdom about how to protect an attached garage from intrusion and fire?
Am I really asking for trouble installing a smoke or smoke/heat detector? Presumably, the garage doors will be wide open for what should be a very brief moment that a running vehicle will be inside, with tailpipe pointing out, and of course someone (the driver) would be present during that time. However, we might have just parked a hot car shortly before catching a ride to the airport, and I wonder if that could set off a smoke say 10 or 15 minutes later.
Also, is a motion detector in the garage prone to suffering false alarms from latent heat waves wafting off a parked vehicle, or from winds blowing through all of the cracks in the garage doors?
thanks!
Bill

Am I really asking for trouble installing a smoke or smoke/heat detector?
This would depend on the fume build up in the garage from the exhaust not to mention local code. I could not recommend a smoke.
Also, is a motion detector in the garage prone to suffering false alarms from latent heat waves wafting off a parked vehicle, or from winds blowing through all of the cracks in the garage doors?

This is certainly possible depending on the location of the detector. We’ve seen motions pick up false readings from registers indoors. So depedding on how close to the door/draft it could be triggered. I shouldn’t think the ambient heat from a idling car would be enough to trip the motion however, again, depending on installation point.

Thank you Tyler,
I wasn’t thinking the car would be idling, just giving off heat because it had been recently parked. I expect the wind blowing through cracks in garage doors could exceed an HVAC register, so I think I’ll skip the motion detector and try to install contacts on the two doors and hope they’re not flaky.

Looks like I’ll be hardwiring a heat detector as well. Spiders occurred to me after posting my question, probably another good reason to avoid smokes in the garage.
thanks!
Bill