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I posted asking what headers etc will fit a 5th ave. I wanna know what you guys are pulling down for mileage in yours and what your combo is. Also what size tanks do they have? Mine might need a carb swap and leanburn delete already .



The first summer I had my 82 Fifth, Stone Stock- between 15-18mpg city, and 18-22 mpg highway. Really depended on how hard I pressed the 'GO' pedal...

Today-
318--Magnum Heads- Hooker Headers- Full 2 1/2" Dual Exhaust system connected to headers and with Flowmaster Mufflers (no Cats)- Crosswinds Intake- Carter AVS carb- Jegs Cam- HEI Ignition (leanburn delete, emissions delete)- recurved distributor- A/C Delete- High flow Water Pump- 3-core replacement radiator- Aux Oil and Transmission Coolers- B & M shift-kitted trans- 3.55 Sure-Grip 8 1/4 rear- 205's sized tires.
Makes TONS of power down low, and runs all day long at 75-80mpg on the highway with zero issues-(just higher RPMS)...and will beat most modern cars hands down. And fuel milage-

10-12 mpg city, 12-15 highway.
Again- depends on the 'GO' pedal and how hard I stomp it.
I also need to run Plus gasoline (89 octane here) because I get some pinging with 87 (regular) and 93 burns tooooooo fast...as in...I like to push that pedal too much when I'm running premium. The Magnum heads up the CR from the dismal 8.5- something to more like 9-something.

Keep in mind that the 5th is basically about as aerodynamic as a Cinder Block, has a large V8 and is choked with more emissions equipment that just about anything I have ever worked on. You are LUCKY to get the kind of milage I got when she was stone stock.

Any way you slice it- a 5th ave is NEVER a good fuel economy car. What it is- The nicest riding Luxury-type car I've driven in quite some time. And Also- About the biggest SLEEPER car I can think of.
No one expects the Grandpa-mobile to eat their lunch in a drag race. That's what makes it fun!

Just my pennies,
CC.