We just bought a 2017 RX450h, upon driving it home in rush hour traffic with temps in the 30s, we lost our cabin heat. The car was using the electric motor as we were going very slow. If the heating system was set to auto, shouldn't the gas engine come on to heat the cabin? What are we doing wrong?

 

That's odd. You should not lose cabin heat. In my Highlander Hybrid, if it's cold out with the heat on and we're mostly running electric, the engine will periodically fire up to keep warm and continue to provide cabin heat.

Was it still blowing, but the air was cool?

 

yes, it was still blowing but cold.

 

Was the car in ECO mode by chance? I believe ECO mode alters the behavior of the climate system. I'd say "no heat" would be well beyond any expectation regardless, but curious if you experience that in Normal?

 

We took it into the dealer, after a little hemming and hawing, they gave us a loaner and sent us on our way. A few hours later they called and reported we had a loose relay. Supposedly works great now, we pick it up later today.
Point of interest, we called a different dealer and the service person told us it was the nature of the beast.

 

^ Glad it's getting fixed. I see you are in WA - are you dealing with Tacoma, Bellevue or Seattle Lexus by chance? Maybe my question is which one told you it was "the nature of the beast".

 

That would be Seattle. We were really surprised at their lack of knowledge of the hybrid.

 

Wow - I'm surprised, but I've never been to the Seattle dealership either. I use Bellevue for service - they've been great, but then again I've not had anything unusual to deal with either.

 

I bought mine at the Lynwood dealer. Mostly because a good friend had a buying experience in Bellevue that seemed odd to me. (Not bad, just didn’t make me comfortable). Car has been flawless, driving back from Alaska today (suppose to be packing now instead of this). I’ll be having my first maintenance visit in Lynwood. So far I have been a little disappointed in level of knowledge and eagerness to share it (everywhere).

 

Lynwood is a bit too far from where I'm at - but anxious to hear how it goes with them!

 

We made it to Lynnwood. The Lexus crew seemed very hospitable and knowledgeable. We had a young fellow go over all of the switches and buttons with us just in case we missed something (hard to look that stuff up in the manual). The original sales guy was there and took a few minutes to make sure we were happy with the car (it is a really great car). We stuck around and read our novels while service went over the car, changed the oil, rotated tires, gave it a wash (missed that area inside the door on the body just like I do). All in all a very pleasant visit.
We drove a thousand miles from home to our ferry departure and then watched the world go by as the ferry worked its way down to Fairhavn/Bellingham. Weather wasn't too bad, snow and blowing snow (hard to see the road in places), roads plowed and not so plowed, black ice and crusty snow, rain and freezing rain. A good test. I am really impressed with the factory tires. I typically change tires out pretty quickly to a better ice tire design. Mileage dropped to around 24. (back to 27-working to 28) in Seattle.
On the drive we encountered temps from +20 to +45 on the drive, the heater did a good job (I assume it takes heat off of the engine cooling system like a normal car), windshield stayed clear mostly and a quick switch on the heating system cleared things up quickly when we about to get fogged up.
Off the ferry and on down to Seattle was great. Visits to a few outdoor veggie stands (we enjoy the Chuckanut Drive and Farm to Market roads).

So in summary. High marks for Lexus of Lynnwood and a great trip in a great car.