Found this from turbobuicks and it is a
different car mag article than the one I know of that reports insane mpg:
"I just joined, I hope this is in the right category.
January 1996 Car Craft magazine has an article called "Real Street Eliminators". A showdown between 7 cars, an 87 Buick Regal 3.8 liter (231ci) V6 Turbo places second. 1/4 mile time is 12.97 at 108.81 mph and they say "quite frankly a ridiculous 46.17 mpg during our 61 mile test journey". They say "we don't know how (this ain't no Geo) but it did it". Stock heads, cam, pistons, crank. Mods are "Lucas 40-pound injectors", exhaust and chip. TH200-4R overdrive auto, but with 3.73 gears. Can a Turbo V6 Buick really get this kind of fuel mileage? Do y'all believe this article? 46 mpg sounds too good to be true. Thanks
The first place car in the article was an 88 Trans Am 5.7 engine. It's 1/4 time was 12.64 and mpg was 30.09. It had a lot of mods plus 6 speed manual and 3.08 gears."
There was further talk in the thread that the mileage was due to a special super lean mpg chip that would "burn the pistons" if you laid into the gas. Which actually is a ridiculous remark since you could build a map that goes rich as soon as you develop load.
But still, here we have the mysterious and as I call it,
Legendary mpg.