The circuit tells an ecu what speed to run the engine at, and states the resistor tolerance at 5%. I am hoping a little 20ish pin ic could do the job - just want to keep the circuit simple as possible.
Thanks in advance
For many applications, I would say go with the analog switch. That said, you have some pretty low resistor values, and you need to be absolutely sure that your on resistance of the switch doesn't do anything nasty.
If you can't convince yourself that it's OK, I'd consider SSR's. You can get them in some pretty small packages. See http://www.ixysic.com/Products/SSRFormA.htm for one product line. You can get quads in small packages -- e.g., https://www.mouser.com/datasheet/2/389/vni4140k-32-974430.pdf