The free maintenance services on my 2015.5 Volvo S60 ended with the 30K one, so on the 40K one where they were quoting $600-$700. I did not have it done at the dealer.
I bought a K&N 33-2388 lifetime engine air filter from Pep Boys, on sale for about $34., and an activated charcoal cabin air filter from carparts.com for about $25, which came to about $35. with tax and shipping.
The engine air filter was easy to install, just unscrew the air hose and disconnect the electrical connection, open the screws around the filter (I could've used a torque screwdriver but a standard flat edged one that happened to be the right size opened them fine), vacuum out the housing and install the new filter. With the K&N filter I perceive smoother acceleration although it could be placebo effect.
The cabin air filter was a real pain to get to, get out and most especially - to put back in. It's under the glove box, to the left, and everything about this process, the angle, the access and the lack of lighting was difficult. While sticking the new filter in I gave up at one point and unscrewed the entire glove box to try to gain better access, but could not pull it out, so I aborted that glove box removal effort and just went back to gradually shoving the new filter in, which it eventually did go all the way in properly. I had to be careful before putting it in that the air flow arrow was directed into the center of the cabin.
I bought two new Bosch wiper blades, 20OE and 26OE, about $15. each, and installed myself. Easy, but make sure these have the right adapters with them. The 20CA and 26CA versions don't all contain the correct fittings.
Then I took the car to Firestone Complete Auto Care where they owed me a free synthetic oil change, and paid them $109. for a brake fluid replacement, and ten dollars for a complete car inspection. It was within this process that I discovered that I needed two new front tires - uneven wear, to the steel belts at 40K miles on the inner edge. I paid for a lifetime alignment, $179. It a leased car that I will buy at the end of the lease. I'm committed now after spending all this, and I'm going to be way over the 36K miles by the end of the year anyway, so buying it makes the most sense.
All said with tax this ended up costing me $899. at Firestone plus the parts I bought, and my labor. However, at that cost I did get two brand new tires and the lifetime alignment. Deducting for the alignment and tires, and new wiper blades, the cost (not including my labor, lol) was about $275. for everything (factoring in the price of the oil change, if I had had to pay for it).
What I can do now, since the car is under warranty is take the car to the dealer for any electronic updates.
By doing some of this yourself, you do save money, but not time.