Best sap remover for car

Avoid dishwashing soaps as they will dull the finish and quite possibly harm the clear coat.

Try "Murphy Oil Soap" in diluted form and test on a horizontal out of the way surface. Dilutued orange oil solvents work fairly well on brake dust encrusted wheels. Should be okay for cars if diluted and washed in the shade.

Quite often, out of the bottle car wash solutions work the best - try it in the shade with the solution in warm water temperature. The idea is to melt the sap and the car wash detergent lifts it off the clearcoat surface. Washing in direct sunlight on a hot day will only get it smeared all over the vehicle.

I used to wash cars every weekend for 2 years as a teen. We live in an area with streets lined with "lime trees" - not the kind you get in Florida, but the kind that aphids colonise and drop sap all over your car.
I would use a dedicated car wash soap - dish soaps often leave smears, even on a clean surface. Warm water is a must - you will be surprised how much better stuff shifts in warm water.
Get the surface wet, with cold water from a hose is OK, then go at it with a good open-cell sponge from your warm, soapy bucket. Work from the roof down to the wheels on one side, then rinse off, with some warm water (cold would be less useful, you want to soften and lift off any crud that the soap has missed/suspended). If you have a lot of sap, try to quickly wet, wash and rinse small areas to keep the sap wet and warm, it will come off more easily. Use a different sponge for really filthy areas like the wheels and lower sills and do these last.
For hot water don't fill your bucket all the way, better to keep filling with hot water than use cooled water.