Kaplan scoring is NOT accurate. You get a much lower score than you would have on the real test for the same perf. I guess it is a result of their "if you score less on the test than on your initial test after a course at Kapln, you get your money back". I personnally scored between 50 to 80 points less on the Kaplan CATs than on the real test.
I actually found that Kaplan CATs were:
- easier on the quant part than the actual GMAT
- harder on the verbal part than the actual GMAT
- scored more severly than the actual GMAT
I really think that the most accurate source is GMATPrep: have you taken one of these tests?