I wasn't aiming to call you out, as such. I just wanted to air my opinion, but thank you none the less for providing some sources :-)

The 45 feet from 30mph is a common figure (the UK government's Highway Code uses it as well).

The cars I tested are normal cars, but I concede I had good tyres and I always choose smooth roads to test on. Once you include:

1. Driver ability

2. Vehicle quality

3. Road quality

4. Prevailing conditions

5. 4 passengers plus luggage

I guess you can explain the difference.