our E34 530i (non-sport V8)had very heavy steering - felt like no power steering at all...
the E39 528i (sport package)had lighter steering than E34 but heavier than 4.6iS
the E53 4.6iS was light
the E53 4.8iS is much heavier than 4.6 and a bit heavier than E39 but not as heavy as E34
the E90 335i (M package) feels like there are little elfs fighting against the steering effort - super heavy

never tried an E70... sorry

The 03 4.4 is mighty heavy to the point of being a bit silly when parking (We have Tundra p/u truck which has pretty light steering)
The 06 4.8iS was quite light and now we have an e70 35d and it is about midway between the e53s. At speed I believe all 3 are similar in feel.

Thanks. Just a point of clarification - Are the 03 4.4 and the 06 4.8is both E53's? If yes then are you saying that your current/latest 3.5d E70 is heavier and tighter compared to both your E53's?

I'm trying to find out if there is something wrong with the PS on the E70 I am purchasing because I felt that the it had a heavier/tighter ps when I test drove it (parking and manoeuvring NOT when speeding). Unfortunately, my only benchmark was my former E53 which felt extremely lighter than this E70. I hope I will have a chance to drive other E70's, maybe that will answer my apprehensions and fears.

Perhaps my post #8 wasn't clear, so I will try again.

There is no single "E53 power steering" and the same is true for the E83, E70, and so on. There were standard power steering systems, and optional ps systems designed to change the assist level. Which is what you are asking about.

I don't have the full matrix of which options were offered in each year, but here are some guidelines. Options varied by market.

X3: standard ps, and optional Servotronic. Standard system varies assist level with engine speed. Servotronic varies assist level with vehicle speed, so you get more assist at parking speeds, and less on the highway. We ordered Servotronic as an option on our X3 and like it.

E53: standard ps, and optional Servotronic. Servotronic was (I think) included on the 4.6 and 4.8, and a priority one option on the rest. That meant a special order.

E70: standard ps, and optional Active steering. Active steering varies the steering gear ratio by means of a planetary gear set in the steering column. Ratio implies the amount of steering angle produced for a given movement of the steering wheel. Active included Servotronic, which wasn't available by itself. All of this will produce a very different feel.

M versions: special ps version called M Servotronic. User adjustable, I believe.

So, comparing an E53 and an E70 depends on which steering options, if any, each has. But a good guess would be that an E53 4.8 had Servotronic, and an E70 wouldn't, meaning the steering would feel much heavier at low speeds, but the same at highway speeds.

Jeff

Great explanation--you have much more patience than I do. Bravo, sir.

Yes, huge difference in steering between the two, have both and always think there's something wrong with e70. Nothing wrong with it just the fun to drive and nimble feeling is gone, just like the new 3 series, the new 5 series, etc. The e53 that I have is a 4.6is and is a far more superior SUV to drive then the e70. You wouldn't know this unless you have both.