67 Pontiac Bonneville Fuel Economy

Hello everyone. I'm trying to get the fuel economy on the 67 Pontiac Bonneville. Specs are 6.6L 4BL OHV 8cyl 400 engine. I've phoned the dealership and no one has come up with the mileage of a full tank of gas. This would be helpful because I need to figure shipping cost vs driving. Thanks in advance.

In new condition at 60 mph the best would be about 15 mpg, gotta use high test also..

By far it's not new. Is that really all the mpg it will offer? Can I do anything to improve the 15 mpg besides an expensive tune up? What do u mean about high test?

You don't know what high test gas is?

ellev8or - He means the highest ( octane ) Premium gas available .

I know its been a couple years since this thread was started but I still have a some questions concerning the fuel economy.

I've had an electronic ignition installed with a complete tune up and a new Edelbrock carb; would these upgrades improve the fuel economy? I'm asking because since the new upgrades and some much needed attention to the engine, it appears that its running a whole lot better than it ever has since I've owned it. Before, I could not drive at least 100 miles on a full tank, which maybe last about a couple days. Now its nearly an entire week of driving before refueling.

Some info on the electronic ignition would be helpful.

Also, what is the fuel capacity or gas tank size for my vehicle? I've checked Google and nothing. AutoZone is showing a 22 gallon tank; is that correct?

Thanks

So what is your mileage, yes 22 gal. tank is correct. What info can we give on the ign., what is it by who?

@maxwedge

The current mileage is 58800. I was asking for general info on the electronic ignition. For example: What's its purpose? Does it improve fuel economy? Was it smart to have installed to my engine?

I'm curious because if its unnecessary then I'll know that it was money wasted and that the tech lied to me.

Thanks