Well, I finally went on a trail run with a diesel today, and I've got to say that it was an overwhelming experience. My opinion now is that it is definitely worse to be behind a diesel on the trail than a carbureted gasoline-powered rig. I couldn't believe the billowing clouds of pitch-black smoke that spewed from this diesel FJ40 that was with us. My subjective opinion that unburned gas is a worse smell the diesel exhaust remains, but with the sheer volume of exhaust that diesel put out it doesn't matter. Wow. The owner said it was a normally aspirated 3.4 litre, and that it won't "smoke" so much when he puts a turbo on it. I sure hope he's right, because it's a beautiful and capable rig, but it sure is odouriferous!
/Peter