Without seeing the actual recipe, I’d say that’s a lot…..
I started using dry white vermouth instead of wine in recipes a few years back on the usually flawless advice of Julia Child. She reasons that, while it’s usually quite easy to find a red wine that "cooks up" well, white wine’s behavior when it hits a hot pan is unpredictable. Heat and evaporation concentrate the wine’s various qualities, so if a cheap white wine is a bit thin or a little too tart or acidic, you’re in for trouble after it reduces in the pan.
She recommends a ratio of about 2/3 cup of vermouth substituted for the dry white wine. And, per Cook’s Illustrated‘s advice, I’ve found the two best choices to be Noilly Prat (and my French isn’t good enough to call it anything other than "Noy-Lee Pratt") and, of all things Gallo.
I’ve never been able to tell the difference; I detect none of the "herbaceous" flavor of the vermouth, and the slight difference in alcohol content doesn’t affect the "physics" of the dish at all.
This has been yet another piece of Julia’s advice that has changed the way I cook. Besides, there are two advantages:
1. The vermouth is cheaper than any wine that would not be dreadful in the pan ($4.00 or so for the Gallo, maybe $7.00 for the Noylee Pratt).
2. I don’t have to steal any of my wife’s Chardonnay for the recipe.
Happy wallet. Happy spouse. I was sold.