500E faithful,
After talking with Benzmac, readling literature, and finally messing with my own car while it was in the air I can say this....the 500E DOES have a limited slip differential.

While we are on the topic of rear diffs, doing a rear diff change to something lower would hurt top end potential as long as we are keeping with the 4-speed automatic. Pop in the 6-speed manual and then the 3.27 or 3.08 isn't a bad idea, but doing either would bring top speed down some. After pegging my 500E's speedo past 160mph that is about your top speed with stock gearing and the 4-speed auto.

The fuel and the ignition are both computer controlled. Reprogramming one aspect is easier than reprogramming both. This is not saying you can't reprogram the fuel/air and ignition... The stock fuel management tends on the lean side so you should be able to get some gains just from that. I've also been told that when the engine gets to 100C, then progressively after that, it takes out timing in 2 degree increments. That is why keeping that engine temp down around 80-85 C is worth 30-45HP.

As was discussed earlier in this forum...the OEM exhaust system is pretty close to optimal on its own. To get any kind of measureable gains you would have to replace 100% of it and/or make some compromises. If you do a 6.0 engine, then it probably becomes a good idea. Before then, you can get much better "bang for the buck" elsewhere.

Example: the Renntech complete exhaust sytem is $12,600. You can buy a 420+HP 6.0 engine conversion from Brabus for $19K. Personally I would rather kick in the extra cash for the real 6.0 engine. To match the Brabus engine you would need a Renntech stage three 6.0 conversion for a sticker of $41K-$50K. (depending on engine #)

Now that we have discussed unlimited budget 500E upgrades here are some "poor man's" tricks that might work on 500E's.

First: replace the clutch fan with an high speed electric of similar size, that ought to free up some bottom end and perhaps improve low-speed cooling.

2nd: put a second 4-prong coolant temp sensor in while leaving the original in the block. The computer will read the underhood temp which is significantly less than the coolant itself. This should enrich your fuel/air mix. Do not use 24/7 as you may over-richen the fuel/air mix. You could also wire in a resistor that corresponds to the temp when the engine feels to be making the most HP.

3rd: pop in some K&N air filters. If there is some restriction in the breathing, they should help. Just keep them cleaned and oiled every 1-3K miles.

4th: put on stickier tires. 235/50/16 or 245/50/16 on the OEM 16x8" rims or 245/45/17 (european OEM) with some 17x8.5" rims. That will let you use much more of what the car has. Actually, putting 235/50/16 front and 245/50/16 rear would let you dial in some more rear wheelspin before ASR grabbed you. The two sizes are only 1.6% different and either isn't very far from OEM RR.

5th: ASR seems to be "less" active while the brakes are applied. Lightly holding the brake or a switch into the brake circuit...

6th: watter wetter can never hurt, previous mention to temperature and HP.

7th: buy a chip from PAD, PMG, or Superchips (anyone who provides a 30 day guarantee) then take your car and the new chip to a dyno. Run before and after. If it works to their claims, keep it. If it does not, return it. When you find the "hot ticket" let us know!

8th: shift the car manually via the stock shifter. As Lou said, you have a great car...now become a great driver. Learn to use all of what you already have at your disposal.

9th: NOx. Okay, that isn't cheap at $750 to $1,500 but for 100HP-150HP at the flip of a switch the results are not either.

That is about it for those. Conventional press states that 500E supercharging is not possible because of underhood clearance issues. What if I said there IS a way to fit a blower under there without major re-engineering... If anyone is interested, email me.

Just my take on tuning these cars...Lee