If you're even remotely active in the GTA Online community there is a good chance you know the name Broughy1322. The Youtuber falls into the extremely small category of those GTA 5 content creators who don't shit their channels full of pointless clickbait videos and the same 3-minute clip multiple times just to get views and clicks. Broughy has been fighting the good fight and testing vehicles as they are added to the game with a purely performance-based method, and is pretty much your best source for vehicle info.
As you all undoubtedly know, GTA Online will soon be getting the Infernus Classic and Turismo Classic, two new rides which will be added to the sports classic class. They're both retro variants of cars currently available in the game currently and are updated versions of models seen in previous games in the franchise.
Info about the vehicles, their prices, and their 3D models have leaked some time ago, so we all knew what to expect in terms of looks for the new cars, but we didn't know anything about their performance. Thanks to the exploitability of tunables in the PC version of GTA 5 however, mods allow players to unlock and load up the new cars in singleplayer early on.
We also know the release schedule for the two vehicles. The Infernus Classic will be added to GTA Online tomorrow, while the Turismo Classic will be released next Tuesday, on the 4th, unless Rockstar throws a curveball and adds the Duke O'Death to the game before the Turismo.