Sounds to me you meant 70 miles per GALLON rather than per tank. That is against the laws of physics for an internal combustion engine that typically loses 2/3 of fuel energy through heat lost.
If they REALLY said 70 miles per tank, there should not be a problem for a 12-cylinder car to accommodate them!
Lib hacks talking to engineers is the mindless talking to the minds.
Yep - I meant gallon. Thanks for the correction.