Only thing I'm looking into is spark plugs, there's mixed information as to when it's due when I google around.
100,000 miles seems a definite they're due to be done. Vaux say 8 years but I've seen sources say 10 years. (As mines under 80,000 miles). So might do that at a later date.
Thing is, what you have to remember, like the 2 year brake fluid change, we dont drive ICE cars. I'n all ICE cars you will replace the front brake pads before you ever replace the brake fluid. My Volt @ 105k still has 40% pad life left from the factory originals, and the braking system is still running @ 71% efficiency, according to the MOT test docs. This tells me, the brakes just are not getting used much, so why stick to ICE service schedules, when the braking system doesnt get ICE use. Mem i plan to change the brake fluid, after i replace the front Pads. That could be another 50k easily.
Same with spark plugs as you mentioned. In the past in both a 2002 BMW 320i and a 2006 i-vtec Honda CIVIC, the spark plugs were 50k mile change items. Now think about our cars, how often does the ICE actually get used? I roughly worked out not more than 30k miles. We got out Volt @ 2 years old with 15k miles on the clock, it had a very high lifetime MPG of 145mpg, and low miles, just 15k in 2 years and 4 months. This told me the 1st owner didn't use it much and did the bulk of his miles in EV mode.
Now when we collected the car in 2014 i immediately reset the "B" trip computer, and it has never be reset since. So i know in 90k miles i have a average MPG of 108, and have used 811 gallons of petrol. Taking an assumption of an average of 35MPG , x 811, means the ICE has only done around 28500 of those 90k miles, 61.5k have been in EV mode. Add say 1.5k of petrol miles for the first owner, and my ICE engine has not done more than 30k miles, as an good estimation, you cant know exactly.
So again, happy to change the oil when the time based computer says so, as it's only every 2-3 years. But change the spark plugs with only 30k of use. I will wait until i have used about 1400 gallons of petrol, then i know the spark plugs have done at least 50k miles of work.