Some observations and/or suggestions based on what you've posted:
1. What tires do you have on your Highlander? They're definitely not all the same, and roll resistance can be significant. I've seen improvements in MPG approaching 10% with tires that have lower roll resistance.
2. Unhook your battery for at least 15 minutes (some sources recommend 30 minutes), to clear the memory in your ECU. Hook the battery back up, then drive in a normal, economical manner (not saying you're not already) so that the computer can relearn your shift points.
3. Give your Highlander time to break in. Six months should do it. I saw nearly a 10% improvement in mileage between when my HL was new and over six months old.
4. Change the location where you're purchasing your gas. Again, I've logged as much as a 15% drop in mileage (10% with my Highlander once upon a time) due to "bad gas," typically off-season blends sold at independent and other stations.
5. What is the breakdown of your mileage, ie., % driven in the city versus % driven on the highway. Also, in the city, how long are your trips both time and mileage? How fast do you drive on the freeway?
1. What tires do you have on your Highlander? They're definitely not all the same, and roll resistance can be significant. I've seen improvements in MPG approaching 10% with tires that have lower roll resistance.
2. Unhook your battery for at least 15 minutes (some sources recommend 30 minutes), to clear the memory in your ECU. Hook the battery back up, then drive in a normal, economical manner (not saying you're not already) so that the computer can relearn your shift points.
3. Give your Highlander time to break in. Six months should do it. I saw nearly a 10% improvement in mileage between when my HL was new and over six months old.
4. Change the location where you're purchasing your gas. Again, I've logged as much as a 15% drop in mileage (10% with my Highlander once upon a time) due to "bad gas," typically off-season blends sold at independent and other stations.
5. What is the breakdown of your mileage, ie., % driven in the city versus % driven on the highway. Also, in the city, how long are your trips both time and mileage? How fast do you drive on the freeway?