There is a link to a really good article by one chaser who survived the storm that someone posted in the Current Events thread. The article describes what it was like. These chasers were also in their vehicles.
ETA: The article linked above calls that tornado an EF3 and it actually ended up, being classified as an enhanced EF 5 with winds up, to 296 MPH ... and it was the widest tornado in history at 2.6 miles wide. My God!