I drive 16 miles of dirt every day behind guys with trucks but not always....they know I love to take the lead in my ZX3. My engine gets VERY dirty!!
I take 1 oz of dish soap and hot water in a spray bottle and soak everything. I let it sit a few minutes and then simple hose the engine off with the garden hose. I avoid nothing but spend little time near the fuse box.
I have 100k on the car now and the engine you can eat off.
I have used commercial degreasers and pressure washers but I'm not convinced that my method a little more often is not any less effective.
One more thing, always with an ice cold engine!!! Never run and then bathed!
2000 ZX3 -Forest green, 99k, drive on dirt all the time- 16 miles of dirt to work daily
2005 ZX4- White, 215 miles, the "becareful" car!!