By the reports of several of the players registered on the forum its clear that the modifier from the Executive Coupe does not stack if you already have the Executive Coupe from the collect 10-event. You will get the stats and the vehicle but the mod doesnt work.
however it DOES stack if you have the evidence burner.
Gree... surely this is a f.. ehm.. mixup? you can call be a crybaby all your want but its hardly fair that many of us (myself included) spent a lot of gold the first time around on getting the Coupe and Im not complaining that your mistake with the street brawl is giving it out for free but if its stackable for the players who have the evidence burner then obviously is should be stackable with the coupe as well! Please fix this...
It would have been equally unfair the other way around. also if you managed to release this PVP correctly I would be equally disappointed if I used gold to get the coupe at the later level and then figure out that it doesnt stack!
Mods have stacked before and people are spending gold based on the history that they stack and expect this to be so, dont go changing the rules in the middle of people goldspending! bad style.
edit: its actually expected and wanted that you will write a reply here and adress the issue, even though if you have no intention of correcting it so its stackable.. I for one would like to know if its an error or if you dont care