This is what an Insight owner did for his engine.
Randall's Insight - MIMA Honda Insight Modified Integrated Motor Assist Tour De Sol
Scroll down to the Engine blanket stuff.
for most engines I would say this is over kill. but for the insight or other small engines it seems great. I have not done this my self no time/money.... But I do have a lower grill block and 75% of my radiator is covered with a piece for corroplast. with what I have done, when I coast with the engine on for about 1/4 of a mile the engine has dropped about 15-20f from 195ish. I have a lot more sealing work to do.