I am intimidated by the newer vehicles. It used to be easy to change the spark plugs or gap them. No longer. What do I do if bad engine things happen? A pair of vice grips  and a ball peen hammer wont help much nowadays.

This item was suggested by many people.

ScanGauge II Ultra Compact 3-in-1 Automotive Computer with Customizable Real-Time Fuel Economy Digital Gauge

Programmable 3-in-1 automotive trip computer, diagnostic scan tool, and up to 37 digital gauges in one (vehicle dependent)
Watch fuel consumption, cost-per-mile, coolant temperature, engine speed, horsepower, and much more in real time
Works on all 1996 or newer OBDII cars, including gas, diesel, propane and hybrid vehicles
Checks for Diagnostic Trouble Codes (DTCs), clears the codes, and can turn off the “Check Engine” light
No tools required for installation, small size fits nearly anywhere in the vehicle

Seems worthwhile if it tells me that the check engine light means nothing I have to worry about until the next check up. But it costs $154, and that seems like a lot of money for temporary peace of mind.