It used to be axiomatic that you must warm up your car. There were several reasons:
1) The choke was required to run smoothly, but that limited RPMs so you needed to get "off the choke cam" before driving off. Anyone else remember manual chokes? Carburetors?
2) You needed to warm up the thick monograde oil so it could splash lubricate the cylinders, and so it could work it's way through the galleys to reach all the moving parts. Anyone alse remember monograde oil?
3) A common claim was that "90% of engine wear occurs in the first five minutes of operation," but this may no longer be true, with better materials, machining, and multigrade (or synthetic) oil.
4) The differing expansion rate of metals means the tolerances whenn warmed up are not met when cold. However, better materials and CTE matching mean this tolerance problem is less than it used to be.
5) Lastly, automakers wanted you to drive off quickly to help warm up the motor, this being part of the EPA cycle for warmup. To get fewer test emissions, they haad to start driving sooner, eliminating warmup. Then they had to tell US to do it or they would be subject to a claim that the testing was not realistic. But the motors still needed warmup for the reasons above.
I still warm up my air cooled VW, since it is an old design, and takes a long time to warm up evenly, being air cooled, and the mismatch between the alloy block and heads, and steel cylinders and pushrods, make for wildly varying valve clearances during warmup.
But new cars only need a minute or two, and I do that more to make sure all fluids are circulating and the temps are rising as they should (no stuck thermostat, for example). This is where Hyp's gauges would come in handy.
Modern fuel injected cars use extra injector duration, not a choke plate, to enrichen the mixture when cold. There is no rpm limit during warmup. This was also done to reduce emissions, and the faster warmup also means less carbon deposits from burning cold rich mixtures.
I have a long downhill drive to start my commute, so it runs for about a minute before I put a load on it whether I warm it up or not. If I didn't, I'd probably still give it about a minute, then drive off.