Not the prettiest, nor the lightest, but the Lister stationary diesel engine eeks out as much as 50% effiency, and is simple to work on and have some maintence concerns (not as easy as driving a car for five years, then buying another with only having replaced tires, gas, and oil). There are stories of a Lister running in Alaska for 40 years continuously. And they hand-crank even as cold as -20 degrees F.

The only sad part is that 99.995% of them are currently made in China or India.