In that case, since you are matching up to LMP3s, then I would suggest using GT3.
Since you are talking about the cars in PCARS2, they are using 2016 specs for the cars. The reason for the regulation changes in 2016 to the GTE class was because the FIA/ACO wanted to "
clearly define GTE as the top category of GT racing and improve its performance compared to GT3, to clearly separate the two classes in series where they compete together (such as TUSC, ELMS and Asian Le Mans)." -
source
If you use GTE's against LMP3, there is a chance the GTEs might actually be quicker. Tis is why IMSA moved the Prototype Challenge class out of the main series.
With the 2016 regulations, the FIA/ACO loosend the rule book. They opened it up to the manufacturers to have more freedom regarding the amount of aerodynamics and how they apply it. Essentially, they created specifically sized "boxes" that define the maximum areas and zones that engineers can work within. Within those boxes, they are free to do whatever they want. Again, the primary reason behind this change was as stated above, to ensure that GTE cars are clearly faster and a level above GT3 for those series where they share the track (IMSA, ELMS, Asian Le Mans). So as of 2016 regulations, it's no longer accurate to say that GTE has "less" aero.
There are several reasons why GTE cars are faster than GT3s. The current BMW M6 is a perfect example. This car only exists as a "GTE" (actually, GTLM) in IMSA competition. It does not compete outside of North America, so technically it is not a "true GTE", although IMSA's mandate is to adhere to the FIA/ACO GTE regulations. Here is a link to the BMW Motorsports site where they talk about both the GT3 and GTLM version (
https://www.bmw-motorsport.com/en/topics/fahrzeuge/bmw-m6-gt3-gtlm.html )
The key differences are:
- GTLM is 50KG lighter
- GTLM has slightly longer wheelbase
- GTLM has wider tires
- GTLM has smaller fuel tank
- GTLM does NOT have ABS
The slightly longer wheel base increases the car's stability and improves the aerodynamics. Wider tires also means the car's bodywork is slightly wider, providing additional aerodynamic gains. Wider tires also mean more cornering grip. Smaller fuel cell means less weight, also add to that a slightly lighter chassis to begin with, and the power to weight ratio just improved a bit as well. All of this adds up to make the GTE version faster over a lap than it's GT3 counterpart.
Overall, GTE cars are bigger, lighter and wider tires. These are the main reasons why they are faster than the GT3 version.
Hope that helped.
Now, please excuse my while I go nerd out some more.....