Automobile(s): '80 Fleetwood Coupe, 1994 and 1995 Mercedes 140 Coupe
Re: Pictures of 425....
More throttle = less manifold vacuum. The light turns on when manifold vacuum drops below a set number. It is telling you that you would get better gas mileage if you didn't step on it enough to make the lamp come on. Think of it like having your wife in the passenger seat telling you to slow down. It's not an indication of any fault. The lamp will come on more if the engine tune isn't really good. Things like worn out ignition components and vacuum leaks will make the engine run with less vacuum.
If you get reasonable performance and fuel economy with the car then nothing is wrong with it.