I don't know much about cars, so I was wondering what keeps the engine and transmission in synch. My 560SEL runs pretty good but it always feels like the engine and transmission are working against each other. I also have a Toyota Tundra and did an experiment. I went down the same hill starting at the same speed (no gas, just cruising) by the time I got to the bottom Tundra gained 15 mph while 560 slowed 10 mph (much heavier car so one would thinks that momentum and gravity would make it go faster), and I could hear the trans making that sound like manual cars make when you go in reverse. By the way Sleepwalker I checked vacuum its cool, kickdown good too, still have to check B switch.

Jerry

 

The two have different gear ratios. I suspect the 560 SEL has a lower ratio (numerically higher) than the Tundra. There are also different tranmission shift variables (for my lack of knowing a better term) that may keep the 560 SEL from upshifting to the highest ratio (numerically lowest) during coasting before the Tundra does.

When I was in school, I was taught that all things fall due to gravity at the same rate. Something about Gallileo or spaghetti or something. The 560 SEL's momentum from the additional mass would carry it further after the terrain flattened out, but not accelerate it. Momentum doesn't cause acceleration.

There are a ton of other variables as well, such as friction, rolling resistance, wind resistance, etc. Too many to call your experiment a valid source of useful information.