Affect Of Weight And Auto Box On MPG ?
Discussion
Just something that came up in conversation and I know there are (a few) bright people on here. 
If you have a 1600kg car with a (4 speed, torque converter type) Auto box car that does 20mpg.
1) What increase in MPG would you get by reducing its weight by 600kg ?
I think it would save perhaps 3-5 mpg more on stop start trips and negligible on a motorway cruise.
2) What increase in MPG if you fitted a manual gearbox to the car ?
Comparing manual to Auto cars this seems to show around 5mpg saving.
However a 1600kg Auto 4.0 V8 Toyota Soarer does approx 20mpg so why does a 1000kg V8 TVR (or similar) not do close to 30 if driven in a similar manner ?
If you have a 1600kg car with a (4 speed, torque converter type) Auto box car that does 20mpg.
1) What increase in MPG would you get by reducing its weight by 600kg ?
I think it would save perhaps 3-5 mpg more on stop start trips and negligible on a motorway cruise.
2) What increase in MPG if you fitted a manual gearbox to the car ?
Comparing manual to Auto cars this seems to show around 5mpg saving.
However a 1600kg Auto 4.0 V8 Toyota Soarer does approx 20mpg so why does a 1000kg V8 TVR (or similar) not do close to 30 if driven in a similar manner ?
Edited by redgriff500 on Friday 21st January 10:35
They've got different engines in different states of tune. The Lexus V8 is designed to be as smooth, reliable and a bit economical (they were really aimed at the US market) whereas the Rover V8/RV8 are designed for power (when in a TVR, anyway).
The weight makes no difference at all once cruising, and the autobox only drinks fuel at low speeds before the torque converter locks.
The weight makes no difference at all once cruising, and the autobox only drinks fuel at low speeds before the torque converter locks.
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