Mpg for a diesel benz seems like fingerprints on a homo-sapien, they are all different from individual to individual and seem to stay relatively the same from birth to death. My 240d got around 28mpg, wasn't affected by tires, alignment, ride height, injectors, load, weight of my nikes, oil type, fuel type, etc. The worst I figured was 27 mpg with bad injectors, clogged fuel filters, bad alignment, discount tires' cheapest rubbers with a busted outer tie rod, and four full grown men and all of their musical instruments. The best was a hair under 29 with just me and ALL of the above fixed. I haven't figured any numbers with my transplanted engine, but I have a feeling they will be different. It's almost as if some where made on a monday after a full nights rest and a cup of coffee, and had mpg in the 30s. And others where made by workers with a hangover or the flu, or maybe someone sneezed while they were making your injection pump.