Remark
If you really take this question seriously, you will stop tailgating immediately. Being any less than 6 car lengths away from the car in front of you is dangerous even if you are paying attention, never mind if you are not.
Conversion
Now just multiply all the numerators together
60 * 6280 * 1 = 316800
And then multiply all the denominators together
1 * 1 * 3600 = 3600
Divide the numerators / denominators to get 316800/3600 = 88 feet / second
If you go 88 feet in 1 second you will go 88 * 4 feet in 4 seconds which is 352 which is about the length of a football field. It is an awfully long way to be inattentive.