It's not an upsell.

I was sitting watching the techs work on my wife's car recently when one of them wandered in to the waiting area to talk to another customer. He was carrying an engine air filter that was in appalling condition. It was clogged with debris and was almost jet black. The tech explained that this was A Bad Thing to the customer but he wouldn't have any of it. He complained about the tech trying to upsell him on things he "didn't need". The tech tried again to explain to him that this wasn't doing his engine or gas mileage any good but the customer kept refusing to pay for a new filter. In the end they had to put the old one back in the guys truck and off he went. It bothers me when people have so little understanding of things that they can't even listen to basic logic. This guy was absolutely convinced that the new filter was an upsell of a non-critical part of his engine. I'm sure he'll be quite happy with his lean-running engine as it overheats and gives him terrible gas mileage. Look; if you own a car, please try to understand a little of how it works. That way you won't get ripped off by unscrupulous garages but equally you will be able to sense when they're telling you an honest opinion of work you really do need to have done.