I read somewhere that it is possible to ask employers to salary sacrifice things like cars and laptops. Can you explain why that would be beneficial versus purchasing those items the regular way?

When you salary sacrifice you don't pay tax on the car or laptop repayments that would have otherwise been considered income.

So overall you pay less tax.

Basically you are using your income prior to being taxed so you pay less tax on your income because your income effectively reduces after you make those salary sacrifice purchases

Other answers here are correct around reducing taxable income, plus I believe that if there are FBT implications on the purchases, the employer is liable to pay them.