2007 V6 Highlander slow to warm up

If you can get it to another dealer, I'd have it checked again. Or, pay a few bucks to a reliable independent mechanic.

How long is "long?" When you say that your mileage "really stinks," how does that translate to MPG and under what types of driving conditions?

Temperature gauges vary on the "normal" warmed up reading, so unless the gauge is marked with temperature readings, the position is relative.

Make sure the electric cooling fans behind the radiator are not coming up while the engine is warming up.

The heater core acts like a radiator, transferring heat from the coolant to the air in the passenger compartment, so it is normal to take a little longer to warm up if the heater is on.

If the vehicle is equipped with the towing prep package, the larger capacity radiator will mean that the coolant will take longer to warm up.

If the temperature is so cold that the computer isn't going into closed loop it's not good for the catalytic converter either ($$$$$). If others don't have this problem also try contacting the Toyota 1-800 service line in the manual.

snipped-for-privacy@pb.com wrote:

I've been barely able to get 18 mph combined highway/city. Dealer said it could take up to 10K miles before I get the best mileage. I can see it getting better after initial break in but I can't buy 10K miles. That seems extreme.

As far as warm up, my wife's Mazda Tribute with 3.0L comes up to normal in almost half the time. My HL takes almost 5 miles of city driving, roughly 5 minutes or more. Today the outside temp was 28 degrees and when it came up to normal, it was even closer to the tick mark that is just below 3:00. We are supposed to have some teens next week so it will be interesting to see how that goes. Thanks for the feedback.

The EPA mileage for the V6 front wheel drive Highlander is 19 city, 26 highway and for the 4WD version it is 18 city, 24 highway. Both have an EPA combined 21 MPG. I couldn't find how the EPA comes up with the combined figure so I do not know what the mix is. For the EPA's annual fuel cost estimate, they use 45% city and 55% highway miles.

Frequent short trips will have a pretty big effect on fuel economy.

If your vehicle has the tow prep package, then 3 to 5 minutes is about what I would expect for the vehicle to warm up at around 32 degrees outside temp. I've noticed that with Toyotas, the bigger the engine, the longer it takes to warm up because Toyota installs more cooling capacity on vehicles with bigger engines.

As far as closed loop operation, the temperature gauge does not have to go all the way to normal operating temp for the ECM to enter closed loop. The O2 sensors have heaters so that they warm up more quickly.

you might be overthinking things....it could just be a bad thermostat.. and an open thermostat will lead to bad gas milage for sure.