If your mopar is you daily driver!

The basics to better mileage apply to any car. Modern cars are doing this well.

From top to bottm of the engine and then front to rear of the car, better mileage can/could result with;

A free flowing induction system. A cold air intake and K&N or equal filter should be used. An open air cleaner is good but breaths in hot engine air. The cold air intakes a little beter.

Tune the carb lean. No matter what carb you have, tune it!
I myself like a TQ on top. (Thogh ANY CARB TUNED RIGHT WILL DO) The small primaries help create a high velocity through the carb, atomizing the fuel well, going down the intake and passed the heads and valves. Speaking of which......

The intake can be swapped out for a really good dual plane. If it is a Hwy. car, and the RPM's are above 2500 at speed, a single plane intake has an edge in mileage because it breaths easier. Cylinder to cylinder tuning must be done to get the best mileage.

Cylinder head. This should be left stock except a good valve job and lifts under .400 should be improved (For stock cams) with the valve job. Good sealing valves and well prep'd are key here.

Cam, leave the 2bbl. cam in. Unless you want to be adverturous and try one for mileage. It is possible, but it could be disapointing in the power return. I'd also say use a roller cam for a reduction in friction, but that cost is plenty.

Compresion ratio. Keep it pump gas. More mileage cn be seen with a higher ratio, but it is also a balancing act with fuel cost of a hgher grade gas. More power can be added to the engine with more compresion. If 1 point is worth 3% more power without adding any more fuel, then this will translate into more efficent fuel useage and the car will go further on the same amount of fuel.

Ignition. A Multi spark unit is wise for low speed operation and a hot and powerful spark after the approx. 3000 combining of spark firing (AKA No longer a multi spark) to burn all the fuel is a top issue.

Distributor timing is #2 on the list of mileage concern areas. Like a carb, tune it well. Time it right.

Exhaust. Headers can help because breathing in was made easy as per above, make it easy on the way out. Proper pipe sizing! Dont do a 3 inch duel exhaust on a stock 273. An H or X pipe can help here as well.

Parasidic drag can be reduced on the engine. No A/C, P/S and a electric fan can help a bit as well.

Cooling system should be up to par as well.

Including the tranny and rear diff. Speaking of a tranny, they like to run cool, so add a coller and a shift kit. Trannys like to shift quickly. They shift slowly for creature comfort, not long life.

Adding an overdrive can help. This wold require you to recalculate the final drive ratio. MoPars OD trans ratio is .69. Use that figure and multiply by the current gear ratio to come up with the new final drive ratio. Example;

4,10 X .69 = 2.8290 (or 2.83 rounded)
2.76 X .69 = 1.9044 (or 1.90 rounded)

Ya think you could use a 1.90 gear ratio? Only if your attempting a land speed record. Here the 4.10 ratio would be excellent to use with an overdrive. The higher ratio helps the car move quick and easy so getting into the final drive on the Hwy. will not consume more gas and gas poorly burnt up in ineffecient burn cycles.

Tires shold be thin and sized to work with the gear ratio to cruise at and in the highest if not at peak torque since at peak torque, the fuel being used is at it's best effeinecy. Humm Spelling! Dang, tired, sorry.

OH, a torque converter can also add mileage. But this can be dicey and expensive to experiment with. Live with the stock one unless it is a factory high stall unit.

Lower the cars height. Align the front. Keep tire pressure up. Synth oil's and al fluids are helpers as well.