I really like my R500. It's my second. The first, I bought new in the latter part of '05, and put 250k miles on it. The second was a barn find in November 2019, (shown below) with a little over 30k miles. Living in California, the second R has 60k miles. With gas prices above $5.50/ gallon, I'm looking for a way to reduce the fuel cost. I thought, maybe there are hybridizing kits. Online has a few, but they don't seem to be real. Does anyone know if this technology is real?

Barn Find 30k+ Miles in Late 2019

 

If there are any, they would be jank solutions that provide marginal benefits. If you want better highway mileage, you can consider swapping in 3.09 differentials from the 2011+ Durangos and Grand Cherokees to bring down the highway RPM. Not sure if the computer can be coded for 3.09 differentials though. Stock on the R500 is 3.70. 3.45 was used on the diesel and AMG ML, GL, and R. Some diesel R320s had 2.92 but they're very hard to find in the US. Much easier to find a Durango/Grand Cherokee differential.