There are two main companies Jim, Heng Long (which mine is), and Taigen, both of which have a range of WW2 and modern R/C tanks and other vehicles in 1/16th scale.
There are 'up-date' parts available, to replace the plastic or nylon parts, such as real wire towing hawsers, metal shackles, metal tracks, PE engine grilles and items such as buckets, jerry cans etc etc.
From what I've seen, there are clubs who really 'go to town' on authenticity, and stage tank battles - there's also an infra red add-on system, which stops the 'target' tank if a hit is scored.
My tank will remain more of a working 'show piece', although it's fun to hear the gun and machine gun fire, and the engine start up and run sound system, with the headlights lit. When the main gun fires, the tank recoils, a little brutally in my opinion, but there's also a metal barrel available, with realistic recoil !
Prices in the UK range from around £50 for a basic tank - no sound or smoke - up to around £200 for something like a fully up-graded King Tiger with Henschel turret, metal tracks and sprockets etc, and they're probably cheaper in the USA.