I find this is extremely dependent on car. I've had cars that felt like you were about to die at 55 mph, and I've had cars that you couldn't tell you were going fast until you were really moving. For laughs, as my wife and I were driving home one afternoon earlier this year on a completely empty stretch of I-5 south of Portland, I casually accelerated up to about 110 and left it there for maybe a minute, then eased back down to normal speed as we came up into traffic. She never even looked up, didn't notice. But then again, we were in my brand new Camaro SS and I'm not positive it even got over 2000 RPM for that exercise, so I guess that's not a surprise.

So I guess I'm saying I agree. Speed limits are pretty arbitrary, there are a lot of things drivers do every day that are far more dangerous than merely speeding. Closure rate, unsafe passes, tailgating, cutting people off, etc.

/don't get me started about how people drive around you if you're towing a travel trailer, what the heck is it with people?

On most roads around where I live, if you are driving exactly the speed limit, you are a slow moving obstacle that is probably more of a danger due to the extreme speed differential with the other drivers who are 10-20 MPH over the limit. I’d hope self driving cars were programmed to deal safely within the bounds of reality. If there is nobody else on the road, sure drive the speed limit. If cars are whizzing past you on all sides you’re a hazard even if you’re obeying the law.