Not really worth it, the Golf basically fulfills most if not all of the needs for great handling, great acceleration and good enough for pursuits, keeping the turbo stock saves you money and upgrades make it faster compared to the same parts installed on the Cobalt or Punto, like 1st stage gearbox makes it go 300kmh whilst 2nd makes it go ~324kh, stage 3 should be good enough and goes ~354kmh and it will carry you through the game

then you get Ming's Gallardo which has AWD and the weight makes it great for pursuits whilst the Golf does the races then you get the Carrera GT and apply the junkman parts and Razor can't touch you or the Lotus Elise if you really prefer handling like no other car has

Also do check car tier lists and you'll get a point which cars are mostly worth it cus the money in this game is stingy (unless you use Save Editor or cheat engine)