What is the role of modernity in Death of a Salesman? Have cars and gas heaters fundamentally changed the American dream? How does Miller view these innovations?

Modern conveniences are at the heart of the American Dream that Willy yearns to achieve, but, in the end, modernity is part of what causes his ruination. When he is young, Willy is excited about the promises of modernity. He says to Linda in a flashback, "Chevrolet, Linda, is the greatest car ever built." However, it turns out that even though Willy works himself to the bone as a salesman, the expenses involved in maintaining a modern suburban life, including the running of his car, are eating away at his profits—and his ability to survive. Soon after he returns home, Linda tells him that the fan belt broke in his refrigerator and that he owes money on the Chevrolet. He says to Linda, "That goddam Chevrolet, they ought to prohibit the manufacture of that car!" The American Dream and the quest for modern conveniences that it entails have turned people's lives into a nightmare.
At first, Willy is excited about the promise of the car, the symbol of modern living, but the bother and expense of it keep him in debt and make him depressed about his ability to make a living. He says to Linda: "The street is lined with cars. There’s not a breath of fresh air in the neighborhood. The grass don’t grow any more, you can’t raise a carrot in the back yard." The car has been transformed from a symbol of freedom and promise to a symbol of his impending death and the claustrophobic pressure he feels. In the end, he kills himself by crashing his car to give his family insurance money.
Similarly, the gas heater is a sign of the way in which modern living comes to harm Willy. Linda tells her children the following about Willy: "There’s a little attachment on the end of it. I knew right away. And sure enough, on the bottom of the water heater there’s a new little nipple on the gas pipe." In other words, Willy has been attempting suicide with the gas heater. The gas heater is a modern convenience that is intended to improve the quality of people's lives. Instead, Miller implies that it, like other modern conveniences, is a way to make people unhappy. Modern conveniences symbolize the emptiness of the American Dream and the belief, which is part of the dream, that material goods will make people happy.