Philadelphia, PA (Best E Casino) - If NASCAR is looking to monitor heat and carbon monoxide inside the Car of Tomorrow, it certainly got a good test over the weekend at Infineon Raceway in Sonoma, California as outside temperatures reached near 90 degrees and cockpit temperatures soared to 130 degrees.

Drivers like Denny Hamlin have complained to NASCAR of heat and carbon monoxide issues with the COT. That prompted the sanctioning body to begin monitoring both problems last week at Michigan International Speedway.

NASCAR continues to check for unsafe carbon monoxide levels, but they haven't found anything yet. They're particularly sensitive to this issue after a number of incidents in their past. NASCAR veteran Rick Mast retired from the sport in May 2002 after he was diagnosed with chronic carbon monoxide poisoning. Two-time Cup champion Tony Stewart experienced sickness from carbon monoxide exposure in a couple of races in 2002, which brought the problem to life.

Carbon monoxide levels with the COT have been a concern since the car debuted in March 2007 at Bristol Motor Speedway. Hamlin complained of headaches and Cup Series director John Darby acknowledged problems with the tailpipe configuration.

As far as increased heat inside the COT, there is a notable difference from the older car. But some drivers, like Carl Edwards and Jeff Gordon, have adjusted more easily than others based on their exercise regiment. For them, the heat is not a problem, it's another area to gain advantage on the other drivers.

The COT is still a work in progress and more issues will arise, but as long as NASCAR and the teams communicate, they will eventually build a race car that is safe to drive.