Source: BBC - Autos - Fuel, tires, brakes, oil: Four car myths debunked There is one error/omission in this article that needs clarification: Actually it needs about 45-55 seconds to heat up the O{2} sensors for the fuel injection system. Once the O{2} sensors are working, the car will or can tune the mixture. There may be other control laws that are specific to that model but without O{2} sensor input, the fuel injection system runs in 'open loop' mode, a look-up table either from the vendor or historical if captured by the control software and maintained in NVRAM or FLASH memory. In the case of our Prius, the control laws will maximize traction battery during this period to minimize the load on the engine. I've gotten up to 35-40 mph on EV-assist with remarkable, short-term MPG with both our 2003 and 2010 Prius. Bob Wilson
But the car will run, just not as efficiently, as opposed to stumbling and stalling in a much older model. I'll use the remote start while stepping out the door on a freezing day to give the car an extra moment to get the oil flowing before moving, but warming up the car is really for creature comfort than a technical need.
Thanks to your informative posts and my move to a neighborhood that can tolerate "odd" driving, I start my cold engine drive with not much more than idle power. If ambient is > 70F, I enter EV mode below 24 mph after about 0.6 miles, and can then glide to a STOP sign. Excellent warm-up efficiency, and only slightly annoying
