It depends... Certain models have more room for improvement. As was mentioned, the M119 can be taken up to 6.0 liters and 420HP for $19K by Brabus. (or 6.5 liters/450HP with a new block and even more cash) Of course, then you will need MUCH bigger wheels/tires. Not to mentioned the mandatory brake upgrade. To cope with all that extra power on a day to day you will probably need to fortify the tranny, diff, suspension, and cooling as well. Cooling is a known problem for 5.0 500E's, I can't imagine that the steroided version would run much cooler... A tuner touched 500E just might be the most brutal car of the bunch but it could also be a real PITA in hot weather.

Then there is the C36. A fast car, not quite 500E fast out of the box, but still pretty damn quick. A C36 has the downside of not being able to have the engine enlarged any. You want more power?...forced induction. Don't know of any existing C36 turbo or supercharger kits but were you to make one...that might be a really wicked little car.

The first C43's should be hitting the used market soon. When they do they are a prime candidate for a supercharger kit (the one by Lorinser springs to mind) that gives them 4.5 sec 0-60's with the 1/4 being somewhere under the 13.0 second mark. Let's say you pick up a used C43 for $45-50K, spend even $10K in supercharger and other goodies, you still have something that stickers under most new factory hot rods that is nasty fast. Most of them will also still be under factory warranty with an option to extend via Warrantech or someone similar.

A 16v's forte will always be handling. Even with a big performance rebuild and/or a turbo it still wont be as wickedly powerful/fast as those mentioned above. But if you can pick one up with a manual tranny, have some fun with the engine, even upgrade brakes/suspension I'd imagine it could still rate VERY high on the intangible "fun to drive" scale.

The new factory hot-rods are also amazing cars. They have just as much, or as much as you can use on the street, power as the *tweaked* cars listed above and carry full 100% factory warranties. Everything should work perfect the first time and just about everytime thereafter. You probably wont find that your gonzo tuned xxx is eating drivetrain parts like popcorn. The downside however, is that it will not be as exclusive and unique as anything you create. The flip side of that is that any factory hot-rod has great resale value, any heavily tweaked car has less resale value.

The 500E in any state of tune will be a brute from hell first. They can handle very well but need lots more rubber than OEM to do that with. Still the physics of 3850+ lbs of car cannot be ignored. Probably the best tuned option given budget and cold weather. Were not for the overheating glitch I'd say it might be the best tuned option.

A C36 is going to handle a bit better out of the box than the 500E. Also, regardless of mods it will always have the advantage of having 400 less lbs to haul around vs a 500E. An even lower budget package would be a early C36 with a 125HP NOS package for those occasions where you could actually use more than the stock car packs. (racing, track use, etc) Since the stock car can often match (usually beat in my experience) the newer C43 (stock vs stock that is) its performance is nothing to sneeze at, at any vintage. With a pair of turbos or a supercharger it would be that much meaner but you run into development headaches if no kit can be found.

The supercharged C43 may be the best option in my opinion. You will have the more nimble handling of the W202 with unholy power levels. It will also have current styling/ergonomics. Not to mention that the car will have a warranty that could still be extended. This is a package that will have the best mix of power, handling, warranty, and price. You could easily spend more on 500E mods than the entire supercharged C43 package. The real "driving" purist may lean towards a heavily reworked 16v, but you could probably "do" a supercharged C43 and a mildly worked on 16v for the cost of a 500E with all the toys. In any case, there really isn't a bad choice among them. Again, it comes down to what suits your individual tastes and preferences.

Hope this helps...Lee