I got the advice once to make sure you can see the bottom of the tires in front of you. As a general rule, your turning radius tends to align with that. This falls apart with big trailers and snub nose trucks, but it's a good start.

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.

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.

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.

I believe this happens everywhere. I think maybe some people lack correct depth perception or something and maybe they are overcompensating for it? It is highly annoying though, I would agree.

Also: TURN SIGNALS, PEOPLE!!! USE THEM EVERY SINGLE TIME FOR THE LOVE OF GOD. EVEN IF YOU THINK NO ONE IS LOOKING OR YOU’RE IN A TURN ONLY LANE. No excuses

Usually this is the result of distracted driving. At a stop light? Perfect time to check your phone! Once the light turns green I give a solid three count then I honk. I'll probably end up shot dead sooner than later but fuck it and fuck those assholes on their phones.

Tyres and tarmac!

I was taught this in driving school. If you’re the last car slowing down, leave a gap of a few car lengths so if a car behind you is going to hit you, it gives you some room to escape either to move up, or enough room to turn out of the lane.

That sounds like some kind of superhero fantasy to me. In what scenario am I about to be rear ended and have enough time to move my car safely?

I usually leave enough space that I could turn into another lane without having to reverse, so if the car in front of me stalls I can go around without too much fuss. That’s like half a car length at best.

You should be able to see pavement under the rear tires of the car in front of you when stopped

I don't leave any space

I just ram them

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

I’m experiencing this daily in Los Angeles. Also people don’t seem to scoot up onto the sensor so the light takes longer than necessary to change (though stupidly half of those sensors are in the crosswalk or even beyond it).

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.