Sorry for the double post but I am answering my own question here... googled "measure sustained download speed" and found www.testmy.net
along with a few others.
As I suspected Charter is using an initial speed burst that throws off the results from www.speedtest.net
Here is my result from www.testmy.net
I have now tried 4 different web based speed tests... then I DL & installed NetMeter and downloaded a 594.13MB demo game to test. The DL took just under 3 minutes (165 seconds), which equals 3.6MB/s or 28.8 Mbps sustained. So I guess I am getting what I paid for!
Dont believe everything these web based tests tell you... thanks to ISPs cheating with speed bursts, etc!