Most of the Cahors vineyards are to the West of the city.
The vineyards were hit not only by phylloxera in the 19th century,
but by a disastrous frost in 1956. The dominant wine grape
is malbec (known locally as côt or auxerrois).
The traditional "black wine" of the Lot is now rare,
as wine-making methods have changed to produce a
softer wine that is drinkable more quickly. Cahors AC
wine must contain at least 70% malbec, blended with merlot or tannat.
If you are curious, there are a few 100% malbec wines produced,
such as Pigmentum (an uncharacteristically inexpensive wine from Château Mercuès),
Haute Collection (Château Eugénie) and the highly praised Prince Probus
(Clos Triguedina).
You can buy a good bottle of three- to five-year-old oak-aged Cahors wine for between 6.50 and 8 euros (possibly double that in a restaurant, of course). Try Château Croze de Pys, Château Eugénie, Prieuré de Cénac (a good choice in a restaurant) and Château Lamartine. A good wine from a good year will be better after a few more years in the bottle; you might enjoy a mature Château Eugénie (Cuvée Réservée de l'Aïeul), available at the winery for under 15 euros. Naturally, the most heavily marketed wines - Château Lagrézette and Château Mercuès - are not always the best or the best value. If you are staying for a while in the area, you'll discover that many of the supermarket specials and even some "bag-in-box" wines are quite drinkable.
As the Cahors appellation covers only red wines, the few local whites and rosés are usually sold as Vin du Pays du Lot. Rosés from anywhere in France are good lunchtime or hot weather wine choices. Try some - they are crisp and dry and refreshing. Acceptable rosés are available in supermarkets at less than 3 euros a bottle.