Toyota prius hsd Manuel D’Utilisation

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Seasonal Cycles 
 
 
Vehicle Types 
Seasonal cycles affect all types of vehicles, not just hybrid.  But with Prius, you are much more 
aware of the MPG changes due to having a Multi-Display constantly informing you of efficiency 
performance.  With traditional vehicles, owners typically are not aware how much of an affect 
climate has on their vehicle’s performance.  They just assume MPG remains relatively constant 
throughout the entire year.  In reality, that isn’t even remotely correct.  Large fluctuations are 
perfectly normal. 
 
 
 
Temperature 
The difference between the warm & cold months is a significant change in MPG.  In the winter… 
The engine takes longer to warm-up, and the engine is needed to operate the heater.  Both cause 
more fuel to be consumed.  The density of cold air is thicker, making it hard to push through.  This 
reduces efficiency.  In the summer…  Running the A/C to keep you cool requires electricity from 
the battery-pack.  That electricity is ultimately derived from the engine, which consumes fuel to 
accomplish that.  So, the more you use the A/C, the lower MPG will be. 
 
These examples of real-world data (from 
shows the effect of 4 separate Winters & Summers with a 2001 & 2004 Prius in Minnesota: 
 
   
 
 
   
 
 
 
 
Traffic 
It is common for people to forget how much traffic patterns change during the winter.  Slippery 
roads cause major delays, increasing driving time significantly.  So even with the benefit of the 
hybrid system, there is still a very real plenty for getting stuck in that traffic heavy traffic. 
 
 
 
Heater 
Heat to keep you warm in the winter comes from the engine.  Hot coolant is circulated through the 
heater-core as long is possible to continue heating the air.  But eventually, it cools.  At that point, 
the engine must restart to warm the coolant again. 
 
 
 
A/C 
The A/C system in Prius is powered by an electric pump, not a pump powered by a belt connected 
to the engine.  That means in can run for a modest amount of time exclusively using only the 
battery-pack, providing a significant efficiency benefit during the summer. 
 
 
Prius User-Guide 
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Last Updated:  2/07/2006