What’s the best after market brands?

Toyota doesn’t make any spark plugs; everything’s “aftermarket”. Toyota might repackage and assign a part no, but it’s an independent manufacturer. There’s a denso plug specd in owners manual on page 714:

DENSO FC16HR-C9

Check with dealership parts department too; just in case there’s been a suppression.

Be careful where you buy too; there have been counterfeits. Dealership or reputable parts place are best.

 

you can't trust anyone but the dealership for plugs, unfortunately

 

I’ve got a local parts place I’ve used for years, especially for plugs. They’re always around 25% less for plugs; never any problems. But yeah, you have to be cautious: better to spend a bit more and no surprises.

 

Don't buy anything aftermarket ever for a Japanese car because all aftermarket junk is made in China. Would you buy a Chinese car? No, then don't buy Chinese parts for your Japanese car.

Mandel's right. Most of Amazon stuff might say brand name on it but it's all coming from China and it's all fake junk. Your labor is worth more than the parts. I bill $100 an hour from my labor which is pretty low being that I have a specialty certificate and hybrid repair. The parts are the least of the expense of most any repair and faulty parts causes immense frustration and comebacks and/or doubting the diagnosis. I will not deal with aftermarket anything under any circumstances no matter what and if you bring your own part to me I'm not installing it. First it implies you made the diagnosis which usually is wrong anyway and second, well, I've have already answered that above.

I believe you're original question was how to improve fuel economy. Big sidetrack here from the original question. So many questions not answered about how old the plugs are and coil packs are not going to help the problem anyway. If you're getting poor fuel economy you're probably looking in the wrong place. This is an assumption because we don't have any information about how old your plugs are and whether or not there's any misfire codes. I have a box full of aftermarket coil packs that you can play with. They all cause misfires and I took them out of other people's engines, LMAO would have been cheaper to fix it right the first time. Would have been cheaper to pay me to fix it right the first time and you could have saved yourself while you're wasted time and frustration and beat up knuckles and God knows how much how many stains to the interior of your car

 

38 miles per gallon is normal fuel economy for a Prius V....

And... What Parker said....