Copying this from another thread...it's more relevant here:
Just putting together what has actually been testified to...
1. There was chloroform found in the trunk. (Vass and FBI chemist)
2. No tests have been conducted to find out what effect a large volume of chloroform would have on early colonization insects. (Huntington)
3. There were gas cans stored in Casey's trunk. (GA)
4. Presumably because no test has been performed on what effect a large volume of chloroform would have on decompositional insect activity no test has been performed to show the effect of chloroform and gas. (just me

)
5. The trunk was opened several times. (Simon Barker, CA, GA)
6. The trash bag was removed from the trunk and thrown into the tow yard dumpster. (Simon Barker and GA)
7. Huntington attempted to compare his study to this case - however climate and conditions are so different I am not certain any conclusions can be drawn. Certainly not for me.
8. Casey had access to the vehicle at the time of complaining of the smell to Amy.
9. CA admitted to cleaning the vehicle.
10. It is NOT known how airtight the trunk was. (I think Vass and perhaps Haskell both testified to this? Maybe? Huntington was never asked if the vehicle he conducted his experiment in was similar in either make or model to Casey's. If he was I missed it.)
11. The body

being triple bagged. (thanks for the reminder Dead Cat)
At the end of the day what it boils down for me is this: a body did decompose in the back of that car and all the factors involved - gas, clean up, chloroform, removal of the body, airing of the trunk, tampering with evidence all adds up to there being less insect activity than 'normal' in early stages of decomp. JMHO from an admittedly non-scientific mind.