My Father in Law's E class estate has had nothing but problems with the rear air suspension. If it wasn't for the warranty he would have had to pay out enormous sums of money. The suspension at the rear failed just inside the three year warranty period and so the replacement parts were covered for an additional 2 years. Luckily. He came out 6 months later and the car was leaning over again. Replaced again under the two year parts warranty. Then he walked out in the morning a few months later and yes, the suspension was sagging again. If it was em, I would pay for the extended warranty, but then nothing might happen, what's why it is insurance, not assurance.