[speedsman]

Quicky for all you 05 build One owners, july 04 onwards I think
What rpm's are people doing in 5th gear say at 50mph,60mph and 70mph.
Older Ones can reply also, I am just trying to work out if the new gearbox is an improvement in terms of ratios.

[MINIAC]

The new transmission will provide better acceleration but worse gas mileage, because more RPM will be required to maintain speed in 5th gear:

50 MPH = 2351 vs 2110
60 MPH = 2821 vs 2532
70 MPH = 3291 vs 2954

RPM calculated for 175/65-15 tires ...

RPM = MPH / (60 * 3.14159 * (175 * 65 / 100 * 2 / 25.4 + 15) / 12 / 5280 / gear ratio)

where gear ratio = 3.351 (new) or 3.008 (old)

[RedUn]

Quote: Originally Posted by MINIAC

The new transmission will provide better acceleration but worse gas mileage, because more RPM will be required to maintain speed in 5th gear:

in theory yes it shud use more fuel......in real life i say it will use less!

reason being at 70mph in a one in 5th gear you are under 3k rpm meaning u actually need to use quite a bit of throttle just to keep it 70! i find once u get to about 90(where permitted) u use less throttle but more revs (more power/torque etc)

with the new ratios I imagine doing 70 u will be above 3k rpm therefore more/power and torque but using less throttle if that makes sense??

basically i'm just going off the idea that it could be more fuel efficient to run at higher revs with a lot less throttle then at low revs with more throttle

[Lawrothegreat]

I agree with redun perhaps in lower gears - but theres a lot more aerodynamic drag and frontal resistance at 90mph instead of 70mph. Its an interesting question - i think it really depends how torquey the car is at lower rpm. Would be interesting to test it out!

[nonsequitur]

There's a thread getting underway to sort out the ideas, experience, opinion, and practical suggestions for MINI owners to generate Better Gas Mileage; How-to Ideas and Experience.

Check it out, and please add your input there too.