My car repair kit:

• multitool with screwdriver bits
• small socket set
• large Channellock pliers
• galvanized wire
• tire plug kit
• radiator leak sealer
• assortment of auto fuses
• self-fusing silicone tape
• hose clamps
• gloves
• jumper cables
• auto jumpstarter with area light, compressor, USB charger, and inverter
• properly-inflated spare tire, lug wrench, and jack
• "cheater bar" made from a length of pipe for lug wrench
• tow strap

Other useful side-of-the-road items like flashlights, headlamps, first aid kits are in the main emergency kit, always kept in the car.

The spare tire (with jack etc.), self-fusing tape, Channellocks, and jumpstarter have all seen side-of-the-road use to keep me moving. The jumpstarter is used far more often for others, as it's much faster and easier to use than jumper cables.