Two of my older vehicles, ha, I like older vehicles, reminds me of me. Have speedometer cables, have to remove, clean, and relubricate them occasionally or that dancing speedometer needle will make you seasick.
Vss is a small permanent magnet rod with a random wound small gauge magnet wire wrapped around in, placed in proximity to a cog gear at the input to the differential that fires small electrical pulses to the input of a microcontroller. Firmware stored in electrical erasable ram plays games with this pulse where it is sent to a digital to analog converter. These use to be very expensive and accurate devices, but now micron sized FETs buried in an extremely small switch. This outputs a proportional voltage that is applied to a voltmeter of the cheapest variety, good ones use real jewels for bearings.
Also just about the cheapest wire and connectors one can buy for connectivity, so don't wonder why you have problems.
DIC should be more reliable, don't even know why the Cruze has an analog speedometer, somebody put it behind the steering wheel so you can't even see it. What's really reliable is my GPS sitting on the left hand side of my dash.
Had a 380 mile drive yesterday on I-94 with a brand new 70 mph speed limit, Garmin said 65 so was reading in the red. Got me to thinking back when Nixon was president signing an executive order to reduce the speed down to 55, but over the years, was increased to 60, 65, and now 70 again. Do this call this progress? Right back to where we were some 40 years ago.
Today, we were suppose to be driving at 300 mph. Could to 160 mph in a plane, but can't afford the liability insurance anymore.