Mildly Infuriating

I leave a couple of feet between the front of my Miata or Wrangler and the next car ahead. I've been driving since the late 70s and this is the first I've heard of the "botton of the tires" rule of thumb. It wasn't taught back in the day (is it, widely, now?) and it doesn't make much sense to me since it's a function of the size and the shape and height of one's vehicle, which can vary greatly, whereas I know where my front bumper is and I can (usually) clearly see where the rear of the car in front of me is, and hence create the appropriate gap. Sure, I might leave more space if I'm on a steep hill and think the person in front might have a manual (another Miata for example) but that's rare.

Up until very recently people seemed to always keep just a couple of feet between cars at stops like I did. This business of "a car length or two" seems like a very new thing - the past 5 years mostly - and that led me to think it's some kind of stupid new internet cancer. Probably some "influencer" telling his/her audience that you should put your dominance on display at stoplights by pissing people off and preventing them from getting through intersections. Or putting your dominance and alpha-hood on display by blocking them from getting into the turn lane at all. Anything to get attention, anything to show that you're not (truly) a nobody, even when you are, because you have power!

I've only been rear-ended once in 45 years of driving. Being a d*ck on the road in order to (allegedly) absolutely f-ing MAXIMIZE your own self-perceived "safety" (from highly unlikely events) at the expense of everyone else is a totally modern-American sort of thing to do I guess. But I'm not doing it.

Tyres and tarmac!

...i try to leave enough space not to touch bumpers when the front car's suspension rocks back under acceleration...

When I took my driving test. The correct spacing was taught as, if you can see their bottom back tires visible above your hood, then that's the correct distance.

So much that it's reasonable.
Example:
A driver fucking up and fumbling the start during shift (for manual). The car could jump forward/backwards and/or roll.
Which is bad.

Just care about your own distance as you can't do anything against those other drivers anyway.

But 2-3 car lengths? It really bugs me when they do it in a left turn lane causing a back up to the travel lane resulting in overall congestion.

This reminds me of one time I witnessed instant karma. I was driving behind someone doing this in crawling-slow heavy traffic, and got to one of those large intersections with such lanes. Here in Australia they're right turn lanes, though that's irrelevant for the story I wanted to share.

So right in front of me there was this car with at least four guys in it, loud music, and an imbecile on the wheel. I got stuck behind him on a single lane road with no means to overtake. He was driving somewhat below the speed limit for no apparent reason and leaving a massive gap before the next car in front. He still left a large gap when we both merged on a crowded multi lane road, and he kept that 3 car spaced gap at every red light stop. He would lag several seconds before starting to move, obviously not paying attention. I honked a couple times to nudge him.

One of those irritating assholes I guess.

Now, somewhere behind me on the lane to the left there was some other guy with a red convertible and an attitude that screamed "YES I'M OVERCOMPENSATING".

We got to the intersection where the turn only lanes appeared, and the idiot in front of me was once again holding traffic as he lagged to resume driving. But the lane on my left, which continued straight, moved just enough to let the red convertible guy right beside the idiot. And then all of a sudden the convertible revved and zoomed right in front and across the idiot, cutting him off and overtaking him on the turn only lane, sliding right in that annoying massive gap he was leaving.

That was the only time in my life I celebrated such a douchebag move. The slow idiot went insane. Started yelling at the convertible, gave him the finger. The convertible was the last car able to turn on that change of lights so the idiot and everyone behind had to wait yet again for green, but I wasn't mad. Watching the car in front of me shake with rage until the lights changed again made up for it. He didn't lag once they went green again.

I don't leave any space

I just ram them

I recall i was driving with a friend, and he was surprised I pulled up, leaving only a feet between my car and the car in front of me. I asked him why.

He said he grew up in an area prone to car-jackings. His dad taught him to leave that extra space in case someone tries to car-jack you. The extra space is so you're not boxed in by the driver in front and can get around them no matter what. Even if you have to jump the curb and escape on the sidewalk.

I agree that the sensor lights are annoying to deal with, but perhaps the driver has a reason.

Are 'road sensors that trigger a light change' a real thing? I thought lights are on a timed cycle.

I've noticed this as well, first time was Texas in 2020. I'd lived in other places prior and never noticed it. I've sinced moved away from Texas, and the bahavior is a lot less common here. I couldn't figure out why people did it. My theory is, people initially stop at a reasonable distance from the next car and pull out their phone. The next car moves a bit forward for some reason, and the person on their phone doesn't notice.

Enough that you can maneuver out of the lane in an emergency.

You should just be able to see the ground under the back tires of the car in front of you. That’s the appropriate distance.