New Honda Fit (Jazz) from “China Times" Taiwan

[JJazz]

Thumbs down.

[Downsizer]

Re improving fuel efficiency, I am very pleased with the Mk 4 economy in urban and rural use, but I do not understand why it is less economical than the Mk 3 at speeds over 60 mph. Surely with the direct drive engaged at that speed, the consumption should be similar? Or is the gearing different? There is no rev counter on the Mk 4 so it’s hard to tell.

[ColinB]

Re improving fuel efficiency, I am very pleased with the Mk 4 economy in urban and rural use, but I do not understand why it is less economical than the Mk 3 at speeds over 60 mph. Surely with the direct drive engaged at that speed, the consumption should be similar? Or is the gearing different? There is no rev counter on the Mk 4 so it’s hard to tell.

When the car is in direct drive, the hybrid kit is just dead weight. Compared to the MK3, the MK4 is lugging around extra electric motors and a heavy battery and getting no benefit from them. OK, it doesn't have the gearbox but the car is significantly heavier. It shouldn't be a surprise that economy at motorway speeds is worse than a comparable pure ICE.

[ahavoja]

Can the Mk3 non-hybrid really be more efficient at motorway speeds than Mk4 hybrid? I'm wondering because the WLTP numbers suggest that Mk4 hybrid would be more efficient.

The WLTP Extra High MPG rating, which is meant to represent motorway driving speeds, suggests:
49 MPG for Mk4 hybrid Jazz
44 MPG for Mk3 non-hybrid Jazz

[coldstart]

... but I do not understand why it is less economical than the Mk 3 at speeds over 60 mph...

Unfortunately I'm unfamiliar with the MK3 (or any of its predecessors)! - The MK4 facelift is my first Honda (probably not my last)

However, I also found the MK4 to be optimized for speeds up to little above 50 mph  (80 to 100 km/h).

So far I was unable to get official information about relevant data like drag coefficient and/or front area for newer Jazz models. (My assumptions so far involve a drag coefficient around 0.32 and a front area of about 2.15 sqare meters - if anyone should have more accurate data, please don't hesitate to PM me! - thank you!)

As we all know, air drag increases exponentially with speed (and the Jazz - for all its benefits - doesn't qualify exactly as a "lean, low-build sportscar"   -  so, it is alone from its build at a disadvantage.

Please do correct me, if I should have gotten this wrong!
From what Wikipedia tells about the Jazz MK3: It never was offered as a "hybrid" but only as a "normal" petrol car.
This changes things enormously fuel-efficency-wise:
- a "normal" car with petrol engine absolutely sucks in low-demand situations like city stop-and-go traffic
- a "normal" car with petrol engine will "shine" during high load conditions (like motorway travel at higher speeds)

Now enter the Jazz MK4 hybrid:
- as you have already found out: It absolutely "thrives" in the city!
- it is a worthy contestant on A-roads
- it literally "sucks" at motorway speeds (even more so above!)

It all boils down to this: The Jazz's e:HEV system was built and optimized for low(er) speed situations.

If your driving profile should mainly consist of high(er) speed motoring, you will absolutely be disapointed by the Jazz's mpg!
(and - imho: you just might have bought the wrong car for your needs)

[Kremmen]

Re improving fuel efficiency, I am very pleased with the Mk 4 economy in urban and rural use, but I do not understand why it is less economical than the Mk 3 at speeds over 60 mph. Surely with the direct drive engaged at that speed, the consumption should be similar? Or is the gearing different? There is no rev counter on the Mk 4 so it’s hard to tell.

When the car is in direct drive, the hybrid kit is just dead weight. Compared to the MK3, the MK4 is lugging around extra electric motors and a heavy battery and getting no benefit from them. OK, it doesn't have the gearbox but the car is significantly heavier. It shouldn't be a surprise that economy at motorway speeds is worse than a comparable pure ICE.

I've driven at speeds up to 70mph and mine has never gone into direct drive with no electric assist. I haven't looked up the Honda video recently but I seem to recall direct drive only cuts in about 75mph ?

[Lincolnshire Rambler]

I cant comment on the motorway fuel economy of a mk 3 jazz because i didnt have before my mk 4 jazz . However my 1.4 petrol nissan Note was a similar shape weight and 88PS power with 5 speed manual -so should perform along lines  as mk 3 jazz ?  I can say the fuel economy of my mk4 jazz is still better than the note at motorway speeds as jazz adds electric power to the direct drive ICE mode as needed . Also regens in direct drive mode when an it can as well . So hybrid tech is still improving mpg over non hybrid even at motorway speeds. Gives improves driveabilty as well .

[Marco1979]

I can compare Mk3 1.3 and 1.5 CVT to the Mk4. Over longer and faster distances (Autobahn at 70 to 80 mph) the Crosstar gets about the same mpg as the Mk3. It is different though: Mk4 will run at slightly higher revs and charge the battery, depleting it over short distances. Mk3 uses its cvt to lower the revs and because of similar drag and lower weight returns similar values. Mk4 feels much faster, more power at hand to overtake or to go uphill. Even more than the 1.5 Mk3!

I recently changed to a Civic e:hev which is much better at higher speeds than any Jazz: lower drag mostly.

Direct drive starts usually around 40 mph; when you select the energy flow screen you can see a cogged wheel appear when the clutch is engaged. This is direct drive (any energy surplus can still flow into the battery).

[Lord Voltermore]

Now enter the Jazz MK4 hybrid:
- as you have already found out: It absolutely "thrives" in the city!
- it is a worthy contestant on A-roads
- it literally "sucks" at motorway speeds (even more so above!)

I wouldnt say it 'sucks' at motorway speeds and above.  But its certainly lost most of its fuel consumption advantage over 'normal ' cars.If you primarily want to do mega miles in a motorway cruiser there may be slightly better choices ,especially if you are willing to  compromise on interior space.  If I primarily carried goods I would chose a van.    Horses for courses.  The Jazz is a good all rounder.

Even full EV's  have seriously reduced range at high speed.   I sometimes see multi trillion dollar Teslas    hypermiling  at slow speed in the slipstream of trucks  to reach the next charging station .  (Like politicians I too can exaggerate and may not really understand big numbers  )

[John Ratsey]

When the engine is in it's most efficient operating range then the fuel economy is good. 60mph+ pushes the engine outside this efficient range and then the fuel economy plummets (aerodynamic losses being proportion to speed squared doesn't help). It's possible that this change in efficiency coincides with the opening of the second four inlet valves which probably happens at around 3,000 rpm (as on the non-hybrid engines).

Here's Honda's explanation of how the current system works: