I've run across some whining about the OM651 in discussions here and there, but have also seen accounts like yours. The stats I can find put it pretty close to the OM654 in sheer potential.

I have a loopy ambition to find a BMW E30 with no engine (was a great one on Craigslist a year or two ago here - good shape, cheap) and put in a 651 or maybe some years hence when they are more available, a 654. I really liked my 325i but the fuel pump issues were way annoying. Had two, electric of course, one an in-tank. I let go of my first one about a year ago, had 450K and an electronic gremiln I could not find. Would run great, still really strong, for 5 to 20 minutes and then conk out, unstartable for 1 to 3 days. But I just couldn't keep it, didn't have room for it. My second had been totaled earlier by a rear ender SUV.

I read that the E220D will do the 0 to 100km run in 8.8 seconds. The E30 weighs nearly 1000 lbs less, the non convertible ones anyway. So I'm wondering if one such Frankencar might have 7.0 second speed and get 40+ mpg. That would be faster than my 325i and that was fast enough for me. I don't need to go 0 to 60 in 5 or 4 seconds. No need. Would just get me in trouble.

I've read of several 606 transplants into an E30 but looks like trouble. Just not enough room. You would think one of these 4s would be more doable. It's a stretch but who knows. And then I'd need to jump through proper hoops to get a gasoline badged car legal for diesel power, I gather it can be done.

Or I could just come down to earth and get an MB with one of those motors. If they ever open the US market for this car.

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Te futueo et caballum tuum

1986 300SDL, 362K
1984 300D, 138K