i tested my speedometer yesterday and found that it is fairly accurate compared to other posts i have read. i used a handheld gps unit. at 75mph on the speedo, i was at 72 on the gps. at 30mph the gps read 29. that equates to about a 4% error. i can definately live with that. i guess not everynes speedos are off by large amounts (most seem to be though).