Man, I've heard lots of noisy Datsun engines. Likewise, Mazda rotaries are quiet if they have a quiet muffler on them, and noisy if they don't.

Fuel economy? Sure, if you get the power of a V8, you also get the economy of a V8. If you get the 69 HP power of an A12, you get the economy of an econobox. Take your pick.

Don't last a long time? Neither do A12s and A14s if they are revved hard all the time. Depends on how you treat them.

Do what you want. But if your dad and friends won't help build the car, then it's not much fun.

Me? I'm sticking with A-series engine.