Rpm for CU2 Euro Lux Auto vs Euro Lux Manual at 100kph

[ahefara]

We have a Euro Lux Auto which at 100kph does 2000rpm (5th gear auto transmission). It is a CU2 built in May 2010.

A friend of mine has a Euro Lux Manual which at 100kph in 6th gear does 2500rpm. This is also a CU2 built in May 2010.

Does anyone have any comment about their CU2 manual and auto rpms at 100kph? I'm interested to hear what rpms readers have.

Surely the fuel consumption doing highway kilometres in the manual would have to be more, yet Honda claim a slightly better fuel consumption for the manual version of the Euro. Any comments?

[buddah51au]

I have a base model CU2 auto & at a true 100kph (by GPS) it is doing 2200 RPM. Best recorded hwy fuel consumption is 6.23L/100

[aaronng]

The gear ratios are different between the auto and the manual. That's why they have different RPMs at 100km/h.

The way fuel consumption numbers are tested are based on combined driving. There is a portion of the test in a suburban area, so the manual gets a slightly better score there.

[Euro08Jaz]

I imagine it also depends on whether it is 5 speed or 6 speed, I think most of the cl9 manuals were 6 speed? well mine is anyway.

[ahefara]

Thanks for your comment aaronng - but help me understand why the manual car uses less fuel when the engine is turning over faster at 2500rpm than compared to the auto at 2000rpm. To me, the manual engine is running faster at 2500rpm (thereby using more petrol) than the auto running at 2000rpm (thereby using less petrol). I am having trouble understanding this.

[buddah51au]

The Manual will be slightly better in urban areas due to lack of torque converter slippage on an auto while the manual has direct drive through the gearbox. On highway cruising the torque converter locks up on the auto giving direct drive.

All Euro's have a 6 speed manual or a 5 speed Auto.

[Euro707]

We have a Euro Lux Auto which at 100kph does 2000rpm (5th gear auto transmission). It is a CU2 built in May 2010.

A friend of mine has a Euro Lux Manual which at 100kph in 6th gear does 2500rpm. This is also a CU2 built in May 2010.

Does anyone have any comment about their CU2 manual and auto rpms at 100kph? I'm interested to hear what rpms readers have.

Surely the fuel consumption doing highway kilometres in the manual would have to be more, yet Honda claim a slightly better fuel consumption for the manual version of the Euro. Any comments?

My Euro is exactly the same as above and sits on 2000rpm @100kph.

I just returned from a 7 day/ 2,650 km trip : Sydney-Mildura-Broken Hill-Dubbo-Sydney. 3 people in car. Only used BP Ultima. Averaged 7.8 L /100. The roads from Hay -west to Mildura and Broken Hill to Cobar are s-t-r-a-i-g-h-t .....and with cruise control locked on a speed of (lets say =a number between 110 and 130kph) makes the journey one of.... "sheer driving pleasure" (couldn't think of a better description !)

Overtaking road trains etc when you're sitting on 120kph -is a breeze. Just use the paddles and the engine just roars to life and laps it up.

Really .......this vehicle just loves being booted at high rev range. Getting this much performance and economy from a 2.4 litre power plant is remarkable.

My previous car was a Subaru Liberty Spec B. Sure - a high performance car ....BUT I would of paid at least 50% more on my fuel bill for the same trip.

[buddah51au]

My fuel consumption has never been that high in 33,500km

[Type R Positive]

7.8l/100kms? On the highway? I get that around town! Seriously.

[SPQR]

The Manual will be slightly better in urban areas due to lack of torque converter slippage on an auto while the manual has direct drive through the gearbox. On highway cruising the torque converter locks up on the auto giving direct drive.....

^^ Spot on!

For those with an academic interest, I believe that the following specs are correct for a CU2 with AT and MT:

AT: 5th gear 1:0.57, Final drive 1:4.44
MT 6th gear 1:0.69, Final drive 1:4.76

Assuming that it is for a non-luxury model with the 225/50R17 tyres: These tyres have a theoretical circumference of 2 x pi ((225x0.5)+(17/2x25.4))/1,000 = 2.0634 metres
(Note: Division by 1,000 to convert millimetres to metres)

At 100km/h, this tyre undertakes 100 x 1,000/2.0634 = 48,463.7 revs per hour (r.p.h.).
(Note: Multiplication by 1,000 to convert kilometres to metres)

48,463.7 r.p.h. / 60 = 807.7 revs per minute (r.p.m).

Multiplying the various gear ratios for the AT and MT gives theoretical engine r.p.m. at 100km/h:

AT: 807.7 x 0.57 x 4.44 = 2,044 r.p.m. at 100km/h

MT: 807.7 x 0.69 x 4.76 = 2,653 r.p.m at 100km/h.

There is no allowance for tyre growth at speed or actual real world tyre inflation or wear or torque converter slip if not locked at 100km/h.

buddah51au is correct on why there is the difference in real world fuel economy.

[buddah51au]

But in reality you can't use the overall circumference of a tyre to gain true figures as once the tyre is loaded with the weight of the car the circumference changes slightly (unless you were to run 60psi).
A GPS is far more accurate than a speedo, I stand by my figure of 2200 RPM @ a true 100kph for the auto.

[Euro707]

7.8l/100kms? On the highway? I get that around town! Seriously.

My fuel consumption has never been that high in 33,500km

Thats great guys........I'm pleased.

I -too get better L's/ kms on shorter highway trips with just me in the car and sitting on 80-100kph.

But, my point was for a trip that long..... sitting on extended high speeds with 3 adults and a boot full of luggage.......

Not bad......

And yes comparing a Spec B.. 6 Boxer engine with the 2.4 L i-v-tec =unfair comparison