GTA 5 recommends a quad core Cpu and the I3 4170 is a dual core and GTA V is a multi core CPU intensive game because of all the moving objects that needs to be processed by the CPU (vehicles, pedestrians, animals, etc.), and there are a lot of moving objects in the world of Grand Theft Auto V (especially on PC). Rockstar games can only optimize the game to a certain point, and at some point the user needs to upgrade their hardware, that's how it works. Sure, there will be dual cores that will run the game, but that doesn't mean that they will have a great experience. I wouldn't recommend anybody to buy a dual core in the year of 2015.
From PCGamer (according to Rockstar):
Minimum Specs
OS: Windows 8.1 64 Bit, Windows 8 64 Bit, Windows 7 64 Bit Service Pack 1, Windows Vista 64 Bit Service Pack 2* (*NVIDIA video card recommended if running Vista OS)
Processor: Intel Core 2 Quad CPU Q6600 @ 2.40GHz (4 CPUs) / AMD Phenom 9850 Quad-Core Processor (4 CPUs) @ 2.5GHz
Memory: 4GB
Video Card: NVIDIA 9800 GT 1GB / AMD HD 4870 1GB (DX 10, 10.1, 11)
Sound Card: 100% DirectX 10 compatible
HDD Space: 65GB
Recommended Specs
OS: Windows 8.1 64 Bit, Windows 8 64 Bit, Windows 7 64 Bit Service Pack 1
Processor: Intel Core i5 3470 @ 3.2GHZ (4 CPUs) / AMD X8 FX-8350 @ 4GHZ (8 CPUs)
Memory: 8GB
Video Card: NVIDIA GTX 660 2GB / AMD HD7870 2GB
Sound Card: 100% DirectX 10 compatible
HDD Space: 65GB