While the article is about the best clay bar alternatives, all of these have some pros and cons.  I also believe clay bar is an irreplaceable part of the detailing process, but all of these alternatives can definitely help and some should be used.  Onto the list, in no particular order…

Decon Towels

NanoSkin AutoScrub Fine Grade Towel is a really good alternative to clay bar.  I find these towels work pretty well at removing a lot of the lighter contamination and it’s definitely much quicker, less fatiguing than using a clay bar.  It’s much easier to hold and covers more of the panel due to the larger surface area.  That said, it definitely has its limitations, mainly that it can’t be used in really tight areas like clay bars.  Also, the clay bar can be pushed a bit harder to “spot-clean” deeper contaminants, whereas the towel tends to just “mush” together requiring more work over one small spot.  The more aggressive decon towels are much better at removing stubborn contamination than the finer ones, but I still prefer clay bars for such tasks.  Lastly, I’m not a big fan of holding decon towels as they tend to shift around a lot making it a bit hard to keep a grip on them, which brings me to decon pads…

Decon Pads

Decon pads, like the NanoSkin AutoScrub Fine Foam Pad, are very similar to the towels aside from two key differences… 1. The pads are designed to used with a buffer and 2. they’re much, much easier to hold than a decon towel.  That said, I would not recommend using these on a buffer as I had a horrible experience with them marring paint to the paint where it needed thorough paint correction.  By hand though I do really like these pads and we use them regularly.  You can read more in my review on the NanoSkin Autoscrub pads, but overall I think they’re much better than the towels and can help out greatly on a badly contaminated car.

Chemicals

Iron removing chemicals are definitely not an alternative to claybar, but should be used in tandem to really minimize claying time and improve paint condition.  For iron removal we normally use the CarPro IronX or Meguiar’s D1801.  For tar removal it’s either CarPro TarX or a 3M adhesive remover.  The iron removers are pretty hands off, just spray and rinse off.  The tar removers do require some effort where you need to wipe off the tar it breaks down after letting it sit on the paint a bit.  Regardless, I recommend using these on a clean and dry car for maximum efficiency because if you do it on a wet car after washing the chemicals get diluted too much.  We normally use these before washing a car if it’s pretty clean when it comes in or after a wash and dry if it’s pretty filthy.  All of these remove so much contamination before you even have to touch a clay bar so I’d recommend using them before any such job.

Polishing

Lastly, this is a technique you can sometimes use to save a lot of time claying a car.  Polishing the paint in certain situations with something like a Lake Country Blue Hybrid Foamed Wool Pad will remove a lot of contamination.  I don’t do this often but it’s very useful if a car has contamination all over such as paint overspray, tree sap, etc.  In these cases you’re basically using polishing as a “decontamination step” rather than the usual improving the paint step.  And just like with claybar, you’re abrading away contamination.  If you’re lucky, you may have cleaned off pretty much everything AND corrected the paint, so all you need next is some claying to clean up a few spots and finish polishing.  It’s not for everyone nor does it make sense in every situation, but when it works it’s a great time saver.

As I said above, I don’t think a clay bar can be replaced and none of these are a true alternative (decon pad may be the closest thing to it), but they can all be used before claying a car to get quicker and better results.