My son has a Go-Man-Go Dodge Charger Daytona with the 5.7. And his MDS allows his Charger to get 18 mpg mixed and 22 highway. I don't know if the 6.1 will get MDS anytime soon if ever. But the mileage from the 5.7 350 HP engine is not bad at all for the power. So much so that Chevy is coming out with their own MDS. Says something about the leaders and the followers. On the highway when his Charger is cruising you can't tell its running on 4 cylinders but... hit the gas and with the flowmasters you can hear the cylinders kick in. I think the 6.1 gets about 14 and 18 respectivley. But don't take it as gospel.