You have stock tire size on there, and/or verified the odometer somehow? That sounds high for an SDL. That's actually on the high side for a REALLY top-notch 124.133, I don't know if I've seen an SDL achieve those numbers before. To confirm, you'd need to follow up with another tank or two of similar numbers, eliminating filling variations. But still, wow... what fuel are you using, btw? Dino, bio, LSD, ULSD, brand, etc?