My '18 SH RLX was getting routinely 28-30 mpg in the summer, and now seems to have dropped to 23-24.....largely same driving style and road conditions. Only one tank full....but seems oddly low.

Is this unusual in your experience, or does this occur due to ICE warming up later and denser air in the cold? Don't recall this occurring last year.

 

My MDX hybrid seems to be more sensitive to the cold compared to my RLX hybrid. I just purchased the 18 RLX in the 1st week in Dec/19 and mpgs have been holding steady at 26-27 mpg. I think what helps is the RLX is garage kept at home and work at the wife's job and I'm stuck outside at work with the MDX (3.0L pushing around +4600lbs w/ min EV mode in freezing temps doesn't help with the MDX). The battery packs don't like cold temps and can drop range by 10%-25% depending on how cold it is.

 

Thanks. I also had let the tires get a bit low too, with one experiencing a chronic slow leak from a nail.

Perhaps all that combined?

 

Driving my wife's SH- RLX around this winter I can say that the ICE runs a whole lot more as compared to similar routes during warmer months. I'm guessing that it has to do with the electric demands on the system and the need for heat which requires the ICE to produce it. Once warmed up it is a bit more similar to summer in terms of hybrid mode usage. If you do a lot of stop-and-go driving and it's below freezing, I'd easily imaging MPG's closer to a non-hybrid situation...

andy

 

I'm coming out of 08 RDX and 11 MDX. Anything above 14-17 city and 19-21 hwy mpgs is an improvement for me.

 

In cold weather the ICE definitely runs more and MPG suffers. One trick to help improve your MPG is to turn on your heated seat and steering wheel and turn off your heater. ICE is required to generate heat for the heater.

For example, if you are stopped at a street light and your battery is warmed up (blue light on dash is off) and ICE is on, try turning your heater off - usually the ICE will turn off right away.

So what I will do is run the heater when I'm above 90 km/hr when ICE won't disengage anyway, and usually turn the heater off below it. I find with my seat and steering wheel on, I don't need the heat anyway.

I have also heard that winter gas is not as efficient as summer gas and that plays a part in poorer winter MPGs.

 

I noticed that my TSX & RLX PAWS both saw reduced mileage in cold weather by 2-3MPGs. People have said that it could be due to the winter grade gasoline but I am not sure what causes the differences.

That said, my MDX Sport Hybrid also seems to drop 3-4MPGs in the cold. If there is an off warm day that is back in the 60s, the MPGs go back up to normal. I have noted that for whatever reason that the MDX will not go into electric mode as soon as it does in warm weather. Some say that it is bc the engine needs to be warm for the heater. Full disclosure: I tend not to turn my heat on in the winter.

 

OK back again with more data. As my weather warmed the mileage surged from 24-26 in the colder weather to now hovering around 31-32!!

Maybe the cold weather blends add to this. My favorite theory is the that the ICE and lubricants, as well as tires, take far longer to warm up to a hybrid-capable operating efficiency AND that the denser air in the cold demands more petrol. The point about the heater made above also sounds very plausible. Added all together, seems to be the difference......BIG difference!

 

This is completely normal. The simple answer is when the heat is demanded because of the cold weather, the ICE engine is running more often, thus your overall mpg is less. When you no longer need any heat in the car because the outside temps don't call for it, the ICE engine is called for less, and thus the mpg increases.

For comparison reasons only, in the Volvo XC90T8 the heat is created by an electric heater so the mpg are not adversely affected in the cold weather, nor is the ICE engine required to be running to create it. The Acura MDX and RLX Sport Hybrids work off a traditional heater that requires ICE engine engagement.

 

I recently moved from 10-12 miles from work for the wife and I with about +70% of it hwy. We are now down to 2-3 miles to our jobs with at 100% city driving. Both the MDX and RLX mpgs are at or above EPA with the little running around we do now for essentials with the lockdown. Still get the below avg mpgs on below 40 degree cold mornings; but, the zero hwy and improved city mpgs makes up the difference by afternoon. Sam's Club gas is down to $1.59 for 91 octane. The last time I gassed up both vehicles back in early-mid March it was around $2.45 (filled up the cars back then because I thought there would be a gas shortage like toilet paper).

 

The interesting fact that few are discussing is that we may have gasoline shortages in the short run. We are drowning in oil and it is cheaper now that at almost any other time in our lifetimes, and we might have sporadic shortages in gas at the stations. If the revenue generated by delivering the gas is not enough for the distribution vendors to fill the trucks and move the product to the gas stations, some stations might run out. In short, keep your tank filled even if you are not driving very much. I had to run the Volvo for just about 2 days straight to keep all of our technology charged as we lost power from the recent storms. For a 40 hour period of vehicle running, the ICE engine ran for less than 2 hours in idle but the hybrid battery was strong enough to operate and charge cell phones and iPads nearly constantly through that period. Fairly impressive in my mind and an unexpected benefit of nearly any plug in hybrid or total EV vehicle. I hope Acura will bring their own to the market, not just for the MDX but the RDX too. It would compete with the Volvo XC40, XC60 and XC90 plug in hybrids, and several other competitors out there with similar size and luxury brand names. Be safe, feel well, and take care of your neighbors.