RLX-Sport Hybrid

Gents,

I noticed something yesterday as I drove quite a bit in the welcomed rain. Although I was not driving any differently than normal on roads I typically drive on in which I get 30-31 mpg or more, yesterday I consistently saw 25-28 mpg. Now I did have the seat warmer on a lot as well as the heat was running along with the AC to keep the windows clear from fog. Tire pressures were at 36 psi and everything else seemed to be in good order. Any ideas?

justnspace

iTrader: (1)

too many variables to pinpoint in 1 day.
you need more data points.

justnspace

iTrader: (1)

if you really really wanted to find out where your loss of MPG came from; try picking up a data logger from amazon.
it'll be in the form of a dongle that fits and plugs into the OBDII port of your car.

then you can hook up this dongle to your android or iOS device via bluetooth to view the data logs, WHICH WILL DISPLAY every single variable and data point you need to figure out where the loss of MPG came from.

But you knew this already, because SCIENCE!

RLX-Sport Hybrid

My gut tells me it was extra drag from driving through the water and the heat being on, but who knows. Just a question I was pondering. Thanks for the tip.

thoiboi

I can't see the seat warmers affecting MPG but definitely the A/C will.

George Knighton

He has a KC2.

The HVAC runs off of the 250-volt system.

George Knighton

I believe you that you believe that your driving habits were the same, but are you sure?

And did you drive enough miles to be sure that there was a clear difference in mpg?

:-)

justnspace

iTrader: (1)

right, JUST way too many variables to figure out 1 day of driving.

thoiboi

Forgive my ignorance,, I'll see myself out now

hondamore

I've notice a drop in mileage recently which I have attributed to the cooler weather. When the temperature outside drops, the car spends much less time in electric-only mode because the ICE needs to run to heat the cabin heater. Less time in electric-only mode results in noticeably poorer fuel economy during city driving. I'm sure the air density factors in to some degree, but my suspicion is that the mileage drop is from the cabin heater requiring the ICE to run.

Also, with the A/C kicking in to "dry" the air and clear the windows, the battery is drained a bit quicker necessitating the ICE to run more often to recharge it resulting in slightly less time in Electric mode and poorer fuel economy.

Finally, the gas companies may be beginning to introduce winter gas as the temperatures drop (at least up here in western Canada where we've had lows below the freezing mark for a while now) which also has a negative effect on mileage.

Just my two cents.

getakey

If the HVAC runs off the 250V system, then it will definitely impact mpg. Not saying that is exactly what you experienced that day, but the EV range and EV assist will be decreased by the heater. In other words, al l the energy used to generate heat is energy that is not used to power EVs

RLX-Sport Hybrid

Yes it was a large enough sample to say there was a difference. I drove about 100 miles on three different segments on routes I have made before many times. My speeds attained and acceleration requested were well within the normal range of daily driving. By that I mean, no jack rabbit starts and in fact I don't think I even passed 3k on the RPMs at all as is usual and customary. I don't drive at warp speed typically as that would get expensive with the local officials just waiting to provide a costly reminder as such. During those three segments there was a fair amount of 40-50 mph side roads, and some highway time in the 70 mph range. I think that the temperature and rain was the cause for the engine to utilize the ICE more like Hondamore said, as well as the heat being used where in the warmer times it is not. If I remember right, last winter I averaged in the mid 20's for each tank, but I am not sure of that. I just thought this might be an interesting topic to discuss today. Thanks for your input everyone.

George Knighton

The EV range is indeed decreased by the 250-volt air conditioning unit.

But...

We claim that it is overall more efficient than a conventional system. Left on automatic, it just does what it does to maintain the temperature and humidity that it should, and even compensates for the time of day and position of the sun.

It is efficient and an integral part of the car''s performance and efficiency.

:-)

getakey

Does the heat rely exclusively on the 250 volt system? I know it would be more complex, but if you could tap into heat from ICE when at temp, that would decrease the impact on mileage. Using ICE to charge battery and then use electricity from battery to create heat is a big waste. Whereas using heat from ICE is using waste.

My experience with both the 2G RL and this 3G RLX (PAWS version) is that the compensation for time of day and position of sun is way over-engineered. I have to adjust temp by time of day compared to never touching it in previous cars

Ugpo

Well, I live and drive in Vancouver and am going through my second autumn, so yes absolutely the rain, or more importantly those wonderful puddles affect your mileage. In dry weather at the same temperature (within 2 degrees) I get 9.2l/100km but come the puddles and my mileage drops to 10.1l/100km. Still much better than my 2010 6MT TL which got 15l/100km avg. period. Have to admit, I wasn't going for mileage with that one.

George Knighton

The heat in the KC2 is provided by hot coolant, just as it is in other cars.

When the gasoline motor is not running, an electric pump keeps the coolant circulating to provide heat to the interior.

If the coolant cools off too much, the gasoline motor switches on.

George Knighton

On my long drive home last night, I was thinking about this enough to make it worth calling some friends and talking about it.

There's something else that was going on to cause his gas mileage to go down. It's not related simply to the weather, alone, or the use of the air conditioning.

While it is true that in theory the air conditioning could drain the 250-volt battery pack enough to start the gasoline motor, this is really only going to happen when the car is sitting still for prolonged periods.

In everyday driving practice, the gasoline motor is going to start mostly because of demands the driver puts on performance, or because of a drain caused by the use of the three electric motors, and the air conditioning drain on the battery pack is far less and far behind the demands of everyday driving.

Everybody believes that the facts could not point to excess fuel consumption, or a big change in fuel mileage, based solely on the increased use of the air conditioning system, all other things being normal.

Now, you weren't actually driving around with the front defrost button pushed, were you?

getakey

that makes more sense

RLX-Sport Hybrid

No GK. I had the Auto setting on which had the AC on at the time.

RLX-Sport Hybrid

Ok now I have more data to share:

Last night on dry roads with no traffic I completed a 33 mile journey and returned 34.6 mpg. Today I completed the very same journey but now in the rain and returned 26.9 mpg. Thus I can only guess that the extra friction of the rain on the tires from the water is the cause for the reduction in mpg. My average speed was exactly the same. My driving behavior was the same. The heat was on both times. It is the same tank of gas. What else am I missing?

hondamore

I would expect a small difference in the rain, but a 22% drop is surprising. Obviously the 34.6 mpg was achieved with plenty of time in EV mode and I can only assume that the rain somehow caused the car to use the ICE more and NOT enter EV mode. Is it possible that the car senses the reduced traction when the road is wet and requires the ICE to be on and the front tires to be driving the car at all times for safety reasons?? Did you happen to check the EV mode ratio for each trip??

I'll call Holmes, you call Watson and let's figure this out.

getakey

that difference is very surprising - it has to be for some reason ICE is used more, but I cannot think why