I imagine that technically it's possible but it would require serious skills in explosives, bombs, not to mention the illegal side of the thing. Given the existing regulations on the SN, I imagine it's more or less the same for chemicals.
It's sure to cause a simple fire is easier, the explosion requires real skills in this area, cars do not explode by themselves.
Every time I take the car I imagine and hope that it will explode, like in spy movies. Unfortunately for me, that doesn't happen.