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Old 05-11-2019, 07:39 AM
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The_bluester (Paul)
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Quote:
Originally Posted by ngcles View Post
Hi Gary,


No, I'm not confused, you've got it right and I'd contend you are in furious agreement with me. The faster you go in an electric over a set distance, the more energy you consume.

The reverse applies (up to a point) in a petrol/diesel because they have gearboxes. As you have conceded, an electric uses much more "juice" at highway speed than in suburban/urban speeds. This precisely is my point. However your contention that petrol/diesel vehicles use also use more fuel the faster they go is incorrect.

My 2012 2.5 litre diesel Mitsubishi Triton uses about 10.5 litres per 100km in city driving but that drops to less than 8.5 litres per 100km in the bush. That's an increase in fuel efficiency of about 20%. This is pretty much the same as all petrol/diesel vehicles. The reality is that as engine RPM rises (not speed per se) diesel/petrol fuel consumption increases. But conventional vehicles use gearboxes to they are being propelled quickly for comparatively low RPM.

Again, I'm not here to compare diesel -v- petrol -v- electric. All I am trying to point out, and you have helped prove, is that at highway speeds, the amount of "juice" you use in the Tesla (and nearly all electric vehicles) goes up and range consequently goes down compared to city driving.

Unless you are going to do your highway driving at 60kmh in the Tesla, you are going to use more "juice" on the open road per kilometre than in the city and consequently there is a reduction in range -- possibly up to 50% 60kmh -v- 100kmh.

They seem to have overcome one of the problems with electric vehicles with this new fast-charging tech. But, there are several others that need to be addressed before they can become truly mainstream.

Best,

L.
Actually I would argue this from the opposite direction. It is not so much that the EV is worse in freeway cruising, it is that they have a big advantage in urban use.

While I believe that the typical EV does trade off a little high speed efficiency for the sake of low speed punch, your Triton will certainly use more fuel the faster you go, aerodynamics mean it is just going to happen, faster = more drag = more engine power required to maintain a speed = more fuel used over a given distance. It is the stop start of urban driving that makes the bigger difference rather than the speed.

Drive from Melbourne to Sydney and back twice, once maintaining whatever minimum speed is required to hold on to top gear (My Navara for instance is a 7 speed auto but does not pick up seventh until 90KMH) and then do it again at 110 and you will measure a clear difference.

The bigger difference is that the EV (And hybrid cars) have a clear advantage in city driving due to the stop start giving them the opportunity to capture energy in regenerative braking that a traditional car can only turn into brake dust, noise and heat. I read recently of a mob developing a two speed transaxle for lower cost EVs to bring motor speeds down into a more efficient range at highway speeds and coincidentally improve their overtaking performance where anything not costing megabucks (Think Nissan Leaf and Hyundai Ioniq) starts to trail off. I am ignoring anything above about 130KMH myself as it is not relevant in the real world of our speed camera infested nation.
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