Thanks everyone for the input on my question regarding the 500E vs 400E. I really appreciate all the comments. The 500E is just is the finest car I have ever driven. The A8 held that honor until I drove the 500E.

Alain

Thank you for your comments! How does the RENNtech sway bar(s) affect the ride over bumps, if at all?

I have had my 928 for about a week shy of 12 years. It’s a wonderful toy! My only complaint is that its difficult to get good service for it. Fortunately, it has never needed significant work.

Regards

…Tracy

I was fotunate enough to own a really gorgeous Starmarked 124 E420. I fitted a 500E sway bar for flatter cornering and was both pleased and disappointed.
On smooth roads the car cornered wonderfully. However, in the city, the ride became very jiggly - to the point where my wife, who is not exactly an enthusiast, would point out the bouncyness every time we went over a bump. Essentially, the function of a sway bar, is to limit suspension travel of one side, relative to the other - hence flatter cornering. When traversing single wheel bumps however, a bar which is not matched to springs/ shocks in stifness, will limit suspension travel at an earlier point in the deflection range of the spring/ shock. This in turn creates a jiggly ride, which can be really irritating.
I removed the bar before I sold the car. I noticed a very tangible improvement in overall ride quality. In future, I would be very reluctant to upgrade the sway bar, without also upgrading the springs at least.
On the subject of E420 vs E500, I absolutely loved my 420 - until I drove a 500E...
The fit and finish of both E420 and E500 are virtually identical. The major difference is the seating. The 500 has firmer, four place seats, which to me, also look nicer. Since I also own a 95 E320T, I can also attest that the seats in the latter are more comfort biased. Other than that, I cannot see a difference between the E420 and the E500 and both of mine are/ were black/black.
In terms of performance, the 420 is wonderful on the highway. At 70mph it cruises at 1500rpm, which renders the engine barely perceptible. The car is not terribly quick off the line and it handles like a tourer. Towards the middle of my ownership of the 420, i became sufficient dissatsified with its handling, that I explored AMG and Eibach suspension upgrades. However, a drive of a 500E quickly lay to rest any notion of keeping the 420.
Now, I can confirm that the 500 is almost as comfortable as the 420, but the handling is in a different league. Its on par with the latter in terms of being an elegant cruiser, while not coddling the passenger quite as much as the 420, but is so much more fun to drive.
Need i say anymore than that I have to fight my wife to drive it. She makes me drive the poxy wagon since she loves the E500 so much. Why? Because its responsive and it makes driving so easy and precise.
Hope my rambling is helpful (jet lag)
Farrukh