Return journey often far less efficient, why?

[page3]

I keep finding that more often than not, a return journey is far less efficient than the outgoing one. Is there some obvious explanation for this mysterious phenomenon?

Here’s an example of today’s journey…

Almost the same journey (although I did get lost on the way back!) but as you see the return is far far less efficient. In this particular case it could be down to altitude because of where I live, but this isn’t always the case.

And other explanations?

 

[Big Earl]

Altitude and wind direction are probably the two most likely culprits. This trip was likely altitude. Other trips could have been altitude, wind or both.

 

[MrMoonUK]

Look at the difference in elevation!

 

[page3]

Look at the difference in elevation!

Hilly up here in the Chilterns!

 

[MrT3]

In your example it definitely seems to be elevation plus a slightly higher outside temperature would make the aircon work harder.

Not in your case but I often find my return journey has a higher speed, I guess I'm just trying to get home as soon as possible.

 

[Mr H]

It's a bit like going on holiday. A nice gentle pootle down to Dover on the way out and then it's warp speed Mr Sulu on the way back

 

[Adopado]

I keep finding that more often than not, a return journey is far less efficient than the outgoing one. Is there some obvious explanation for this mysterious phenomenon?

Here’s an example of today’s journey…

View attachment 846231

Almost the same journey (although I did get lost on the way back!) but as you see the return is far far less efficient. In this particular case it could be down to altitude because of where I live, but this isn’t always the case.

And other explanations?

Gradients make a huge difference. I drove to our nearest small town 15miles up and down hills but on average I did 114Wh/mile (no AC and slow driving and no wind. ). Of course it was because my destination was lower than my start point at home. By the time I got home the 30 miles average for outbound/inbound was 164Wh/mile. (Still a “record” low consumption for me!) The difference is purely down to start and finish elevation. That’s why you should never take a one way journey as an indication of your car’s range capability. You need to return to your starting point to even things up.

 

[NewbieT]

I’m Winter, pre- heating / scheduled departure makes a big difference when leaving home. Often not possible on the way back.

 

[Overworked]

When I drive downhill to the shops 8 miles away I average about 198 Whr/mile, when I drive uphill back home it is consistently about 300 Whr/mile. Strange that.

It happens every time I repeat it.

 

[Adopado]

When I drive downhill to the shops 8 miles away I average about 198 Whr/mile, when I drive uphill back home it is consistently about 300 Whr/mile. Strange that.

It happens every time I repeat it.

True! It can be obvious when you are aware of driving fairly consistently downhill but often you don't realise because you have been going up some significant climbs as well as going down some others. In those situations it's only when you actually look at the starting point elevation and the end point elevation that you notice it. You wouldn't think that an elevation change of about 120 metres, from start to finish, spread over 15 miles would make much difference but it significantly affects consumption. ... and don't even mention wind direction!

 

[Overworked]

To be fair, I know that I am going downhill as Tesco beside Montrose harbour is at sea level and as I live in the highlands there is a clue there!
... it also has a free podpoint charge point so I usually "fill up" when shopping and finish my trip with the same or more fuel than I started with.

Frugal or thrifty is what I call that

 

[page3]

When I drive downhill to the shops 8 miles away I average about 198 Whr/mile, when I drive uphill back home it is consistently about 300 Whr/mile. Strange that.

It happens every time I repeat it.

I’d have thought though the extra power used to initially heat/cool the car would go some way to offset the return journey, but it appears not.

 

[M1tch]

I keep finding that more often than not, a return journey is far less efficient than the outgoing one. Is there some obvious explanation for this mysterious phenomenon?

Here’s an example of today’s journey…

View attachment 846231

Almost the same journey (although I did get lost on the way back!) but as you see the return is far far less efficient. In this particular case it could be down to altitude because of where I live, but this isn’t always the case.

And other explanations?

How do you get that level of info?

 

[PITA]

It's like a Dog...

Full of efficiency going out for a walk...

... trying to get it back home quickly again, not so much.

 

[Mr H]

How do you get that level of info?

TeslaFi

 

[GRiLLA]

Hilly up here in the Chilterns!

Chilterns also here, (pretty sure I've seen you), and yes its the elevation plus slightly more eager to get home.

 

[M1tch]

TeslaFi

Wow! Signed up last night and can’t believe the amount of detail. I think I’m going to waste a lot of time reading facts and figures on my drives!

Thank you for the pointer though

 

[Adopado]

I’d have thought though the extra power used to initially heat/cool the car would go some way to offset the return journey, but it appears not.

Yes, it does in the winter, depending on journey length, but not at this time of the year. We're at "balanced' temperatures at the moment around here ... i.e. no particular requirement for heating or cooling. If I'm driving on slow roads I will sometimes crack a window and leave the HVAC off completely. Presumably not much need for too much battery temperature support either.

 

[Adopado]

Chilterns also here, (pretty sure I've seen you), and yes its the elevation plus slightly more eager to get home.

View attachment 846757

Good example.
I use near enough 50% more energy getting back from Edinburgh than I use getting there (800ft elevation change over 48 miles). The first time I checked the car estimate of percentage it would take to get there I didn't believe it ... it seemed too optimistic ... but it was spot on.

 

[Irata]

Getaway drivers often experience this effect.

I find it depends which relative I have been forced to visit.