Ok my oldsmobile family..I have a question for u since we are all at home bored. Can someone give me a idea what the difference between these two tachometers that sit in the front of my 66 cutlass on the middle console? One is obviously a rpm tachometer and the other has something to do with fuel economy. Any help would be greatly appreciated. Thank you and please stay safe.

 

I believe the 2nd is a vacuum gauge. Others can verify.

 

The first photo is the tachometer that was used on the 1964-65 consoles. The second photo is the performance gauge (really just a vacuum gauge) used on the 1966 consoles. These gauges were standard equipment on the console in those years. You couldn't get a console without the corresponding gage, and you couldn't get the gauge by itself. Today people have mixed and matched, but when the cars came from the factory, all 64-65 console cars came with the tach and all 66 console cars came with the vacuum gauge. The factory tach for 1966 was the "sidewinder" tach that bolted to the left side of the dash pad (or the in-dash rally pac when that became available late in the 1966 model year).

 

I remember those vacuum gauges (performance gauge) It bounces around alot in conjunction with the accelerator/engine load. It was just cool to look at as a 12 yr old riding with Dad. Cool to look at. Good memories!! Too bad cars aren't as cool as they used to be....