Most auto sales reps get paid on commission. Therefore, they must work hard and become better at sales to make a comfortable living. The going commission for most auto sales reps is 20 to 30 percent of the gross margin, according to Quora.com. Thus, a sale rep that sales a car for $20,000 that costs the company $18,000 would make $360 to $540 on the sale.Sales reps must be willing to negotiate. Savvy buyers know what cars are worth today and won't spend a penny more. One way sale reps learn to negotiate is by knowing al the features of their car versus comparable vehicles on the market. That way if their cars are priced slightly higher, they have an explanation. Their vehicles may have more horsepower or more power features. The heated seats may cost more if the competitive car doesn't have that feature.Sales reps should always stress benefits over features, and try to upsell customers on cars. Benefits include better gas mileage. For example, hybrids get better gas mileage than cars that operate strictly on gasoline. Safety is another benefit. Customers want to know their families will be safe in cars. Therefore, top auto sales reps may study safety charts, and emphasize that benefit if their cars are highly rated in safety.Auto sales reps must also listen to what their customers want. They should not push compact cars if the customer wants a sedan. Similarly, they should focus on just SUVs if that is the customer's preference. Listen to the features the customer wants, and the price range they are seeking. Just like other products, customers are more likely to buy if they get want they want.Auto sales have been traditional slow since the recession of 2007. Many car dealers have used incentives, including manufacturer's discounts. Sales reps need to know all the selling tools available. Thus, auto dealers must continually apprise their reps about special deals. Also, the sales rep should wait till the negotiation process starts before getting into discounts and other specials. These tactics make for better sales closes than benefits or selling features. The process on negotiation in auto sales takes practice.