it's not as good as it sounds. the 325e and the 528e share the same eta style motor, just a different size. when the 535i was introed in 85, it got better mileage-in real life-than the 528e did. i never saw 36 mpg in a customer's car. 30 maybe, under perfect conditions. and it's not a simple design. volvo b230 is a tractor engine compared to a bmw 6, eta or otherwise. break a timing belt and they bend valves. need to adjust the valves every 15k. if the job isn't done right, the idle suffers. volvos RARELY need adjusting. to pull the cam out, you have to pull the head first. and you will have to pull the cam if you don't adjust the valves, they wear out. power, yes, they do better than the b230, those 2 extra cylinders help. wanna a good eta motor? look for a super-eta in a late 325/528. i think the 88-up are those type. you'd have to look at the bmw boards for that. there's also a bunch who take the 524td cranks, use them in the etas and do other stuff to make them go. hth, chuck.