beaters what options do us mopar lovers have?

A slant six Dart with modern engine controls - electronic ignition (a must) and throttle body injection (Megasquirt or latest Holley Projection) should be capable of 30 mpg hwy. If MPI (requires customized intake manifold), even better. A slant + 904 trans is almost free, but modern controls would be >$500.

Of later engines, the 2.0 (or 2.4L) is best. If pre-1999(?), insure it was upgraded to the MLS head gasket since the early gasket design leaked oil (my 96 started at 39K mi). The 2.4L has almost as much HP as the 3.3 V-6, just let it spin to where the 4 valves/cyl flow. In a small car, should give >35 mpg hwy.

At the other end, the 3.8L V-6 is basically the LA small-block less 2 cylinders (2 valves/cyl & pushrods). My 4500 lb minivan has one and rates ~24 mpg hwy, which shows what modern engine controls allow. That is why I suspect a slant six (3.7L) in a Dart could give good mpg, and the few who modernized theirs claim such. There is a newer Mopar V-6 I don't know much about.

New engines can be problematic. The crank sensors can fail and strand you, rubber timing belts and pulleys break or skip, more places to leak oil (especially OHD cam). Aluminum heads are unforgiving of over-heat. And parts prices can be outrageous, especially for new engines.

The latest engine that caught my eye is a 4 cylinder option for the new Ford Explorer. It has more torque than the V-6, over a very broad range, and only slightly less HP. This is mainly due to extreme complication - direct fuel injection, turbocharger, variable individual cam timing, etc. They haven't yet stated mpg, just say "20% better than old Explorer". Neat technology, but a long list of parts that can fail. Only so much you can do if moving a big beast.