Performance mods that cost nothing to very little that will increase horsepower/torque, gas mileage, reduce carbon footprint, less waste and save time and money.

If you want to monitor your improvements you can get an OBDII diagnostic scan tool with live data feed for $20 and download a free Torq Pro app. You can measure 0-60 mph times, gas mileage, airflow rate, engine temperature, emissions rediness, clear trouble codes etc.. You can monitor after each mod or wait until you done all your mods to see improvements. Here are some things I have done.

1. Check tire pressure. Rolling resistance is reduced with properly inflated tires.

2. Use full synthetic motor oil. Less friction, motor runs cooler, more hp/mpg and longer between oil changes. I use Supertech 0w-20 from Wally world $14.88 for 5 quarts. That’s under $3/qt. Check out the results from the synthetic oil shootout on U tube. It scores higher than the # 1 (Mobil-One) oil. I use the Ultra Synthetic XG7317 longer 20K oil filter. It has twice as much filter media than the XG6607 20k filter which is the recommended filter from the manufacture. I always try use a longer filter if available. You can ask the manufacturer if there is a longer version of the recommended filter. You can send a sample of your oil to an oil analysis lab. You would be surprised how long you can get out of an oil change. Less changes less waste oil and filters in the land fill. While you are changing your oil, go ahead and replace your transfer and differential gear oil with a full synthetic. I use Supertech 75w-90 API GL5. 1 qt. under $7 and good for 100K miles. It has a much higher shear strength and lower rolling resistance especially in cold weather than conventional gear oil. It runs much cooler in the summer, reduces friction, resulting in longer lasting components.

3. Drop in a K&N air filter under $50. Clean every 50K miles. 1-million-mile warranty. Never buy another air filter and no more old filters in the land fill. Increases air flow over regular filter more air flow = better hp/mpg.

4. Check the lowest temperature record where you live. Mix your antifreeze mixture to match that temperature. Premix extended life antifreeze is 50/50. My mix is 45/55 (antifreeze/H20) Which is rated at -17.3 degrees (40% is -6 degrees and 50% is -28.6 degrees). Use bottled drinking water not distilled. My car runs 3 degrees cooler at that ratio. Better hp/mpg. Extended life antifreeze is good for 5 years just adjust with drinking water for your climate.

5. My idle was just a little high. Did an idle relearn and right on now.

COVID-19 time at home. I had to do something. I’m a little stir crazy. Stay safe and I would like to hear what other mods people have done. Thanks

Most likely not a popular choice, but going with puny smaller tires increases acceleration.

I prefer big all terrains myself. Slow and heavy, but more aggressive looking.

Dang, that's one long topic title.

Since you've got some free time on your hands, you might find this thread of interest.

2019 Nissan Rogue SV AWD 2.5L - Acceleration and MPG Improvement Thoughts

whats is the best affordable OBDII diagnostic scan tool for 2015 Nissan rogue?

You can get the Veepeak. It cost $11 or $12 for the Android compatible.

Don't like the K&H air filter. I had one in the other car and after sometime the filter lubricant migrated and covered the Mass Flow Sensor causing rough idling and more fuel consumption...

I'm sorry RGOLD you had problems with your K&N air filter. I've never had a problem with them. Maybe it was over oiled from the factory. Seems like it would have thrown a MAF code. I've been using K&N filters since the 70's in my motorcycles. My old foam filters would deteriorate after a couple of years and I was constantly replacing them. They claimed to increase air flow but at the time I couldn't measure it. I did notice a little more intake noise and re-jetting my carb a little richer helped the performance. Now, with diagnostic tools and live data you can measure you air flow with the stock filter and compare with others. K&N recommends you clean your filter every 50K miles. I clean mine more often than that and have not checked my air flow when it is dirty. That might be a good thing to do next time before I clean it. I guess I've purchased about 20 filters over the years and never had a failure. I'm a fan.

Why drinking water instead of distilled?

Water is vaporized into a gas and then condensed back into liquid so you have pure water and all its impurities are left behind, including calcium and magnesium. This leaves you with distilled water which is deionized and acidic from the H+ ions. Over time the water will attempt to balance or correct the PH so, it will actually strip metal from your radiator and engine block. This could cause cooling system component failure. I don’t know, but I thought about it and maybe that’s why years ago I would do a flush and fill my radiator every year. Eventually, I sprung a leak in my radiator. I used distilled water and coolant and nothing poked a hole in my radiator. I soldered it and it sprung another leak and again and then a new radiator.