BF1: Total Mass:
530 kg (1323 lbs)
http://www.lfs.net/?page=contents&car=bf1
UF1: Total Mass:
600 kg (1323 lbs)
http://www.lfs.net/?page=contents&car=uf1
please tell me how 530 and 600 kg both equal 1323 lb

And here's a test. Which one is wrong. Bet you can only do it via Google or equivalent.

UF1's weight is correct, you can see the difference from ingame though, because the bug is only on the website.

600 kg = 1323 (rounded up) lbs
530 kg = 1168 lbs

So yeah, UF1 is right.