LOL I’m in Texas and get better MPG in cold months. The hybrid battery (lithium ion in my 23) is not happy when it’s over 95 outside. I get around 42 in cold weather including all last winter but got 35 when it was 100’durijgbthe Sumer. Also summer means thin air, winter is dense air.

inwas happybwhen the temperature dropped in fall and mpg went immediately back to the 42-45 range. I drive in normal or sport mode on 18 inch wheels and I drive fairly aggressively almost all city driving in heavy traffic.

my last hybrid was NiMh and did better in warm months but not so great when it was over 100 probably because o crank the AC hard and sit in a parked car often on the phone due to my business.

i read somewhere that energy saver low resistance tires only add about 1-2 mpg but cannot recall where.

 

Which model of Kenda tyres? I would like to see the rolling difference between them and ES.

 

Another reason is that the heater core needs hot water to operate the heater. Therefore, the internal combustion has to spend more time running - plus the ICE has to run more frequently to maintain the minimum operating temperature during cold weather. In electric cars, they use electric heaters but hybrids still use the internal combustion engine as a heat source. This also explains an additional drain on the batteries of electric cars during cold months - although perhaps balanced out by electrical consumption of AC during hot weather…

I seem to get the best mileage when temps in the 60s and 70s. I have only hit the high 30s in the very coldest winter months when the temps are well below freezing.

 

It’s not the weather/ temperature, it’s the winter blend gasoline.

 

It is multiple factors and the gas is a pretty small one at least for my car. I get the best MPG on cool and cold days in fall and winter in my hybrid. Extremely cold days the MPG falls due mostly I assume to the engine having to run more often for the heater to blow warm air in the cabin.

Density of the air is a factor. Hot air has less oxygen per cubic liter.

Performance of the hybrid battery is a factor.

mybhubrid gets worse mpg on days over 95F

someone above saidbEVs use electric resistance heaters, that’s not true with many (all?) modern EVs which now use heat pumps which are essentially air conditioners running in reverse.

 

So if low on freon or have an AC problem in winter then no heat. My hybrid sounds better and better.

 

Because it takes longer for the engine to get to the desired temperature, the hybrid batteries (especially Li-Ion) do not perform that well when cold, etc.

 

sure a gas engine uses engine heat to heat the cabin, but it also is a bunch of extra equipment an EV with a heat pump doesn’t have

but yeah I love my hybrid, it’s my second. My next car hopefully is a plug-in hybrid with 40 or more miles of EV range and maybe 300hp that’s my dream ES

 

So here is an update: Drove again to Boston and back and averaged 37.8 mpg. Filled up with regular unleaded for the last bit and got about 38.2 mpg. Last night was the first time we got under 400 miles to the tank, before that it was 488 or so. We have decided to order the original equipment tires (Michllin Energy Saver a/s) from Costco so they will be available in 1 week. I’ll update you all then.

Goodbye Kenda Venza UHP a/s Tires

 

Unfortunately yes. Tires can make a big difference and as the car ages. Those Michilins may have given you good MPGs but I doubt the winter handling was that great. It's a trade off. MPG, Tracktion, Noise.

 

Oh - Your hybrid motor does not need premium gas. You may gain some HP and maybe 1 to 2 MPG. But its not worth the price difference. So your dealer is full of it any your results are correct. Spark plugs should not have made a difference either since they sould last for 100,000 miles.

 

My mileage dropped when I switched tires from the Michelin Energy Saver to Continental Extreme DWS06. Not 9 mpg like the OP but probably 3-4 MPG on average. No regrets however. The energy savers would be great if I were in Arizona or something but they're near worthless on any amount of snow or ice.

 

$47 summer, and 38 in Winter is exactly what I get. The mileage started dropping as soon as the weather started to cool off even without the snow tires are on. The engine has to run more often in the colder weather to keep the engine in the sweet spot to maximize fuel efficiency. If the engine runs more, the more fuel it will use.

 

After five years and 63,000 miles, my ES300h has averaged 43.2 mpg. Every cold season has dropped the fuel economy into the upper 30s. All of the mentioned factors contribute to this normal pattern. I recommend using Top Tier gas and monitoring tire pressures. I would not recommend changing tires or modifying/servicing the car based solely on cold temp fuel economy.

 

You guys must be in a cold or cool climate, because in Texas I get a lot better MPG in every season other than the summer. It’s a 20+ percent loss in the summer for me.