Originally Posted by b.wihardja
Without lap timer, can you feel if your car is going 1 second faster or slower?
1 second, probably. .2 seconds, probably not. That being said, sometimes you can just tell when you're getting through a particular corner or sequence of corners faster or slower. Sometimes you know you just went faster through a corner because you're suddenly over-shooting the next one due to carrying more speed.
If there are other people on track, and you know how fast they are, you can also compare whether you're catching them, staying even, or losing ground.
You can also tell if you're making mistakes: taking corners too wide, hitting things, etc. If you're making mistakes, you're losing a lot of time, and that's the first thing to fix.