During the Thanksgiving Holiday we drove our 2018 Toyota Yaris iA (Mazda2 in disguise) from San Jose to LA Norwalk for 355 miles one way. I totally forgot to turn the TCS off and once we got to LA Norwalk and filled up the gas again at Costco which always has very long line waiting in California, I checked the AVG MPG info display which hasn’t been reset for a long time, 38.4, increased from 37.8 a bit at the Costco gas station in San Jose just before the trip.
On the way back yesterday I turned the TCS off the Yaris definitely behaves just like our CX-5, the car feels peppier which makes me believe the gas mileage should be improved. Wife drove the first part and I could hear the engine was roaring a lot in the mountain section on I-5 north of the LA. We stopped at the first rest area and I started to drive. I saw the AVG MPG showed only 36 which is worse than I expected. I immediately noticed the “SPROT” amber light was on in dash, and that’s why the engine revved very high in 4th or 5th gear even at 70+ mph! I turned the Sport mode and TCS off、reset the AVG MPG、and drove the next 200 miles. Even though there was a 40 minutes of stop-and-go traffic on I-5 due to a car accident, but when we stopped at the rest area and I checked the AVG MPG, I was shocked to see:
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We can see the “TCS OFF” icon is on in dash, but I’ve never seen such diesel like average MPG before, 49.2!
When we got to Costco gas station in San Jose after some mountain road driving on Hwy. 152, the Avg. MPG display still showed 46.0, and we drove 70~80 mph whenever possible, didn’t slow down trying to get better gas mileage.
The MPG calculation based on gas pump is 41.3 from SJ to LA with TCS on, 43.3 from LA to SJ with TCS off (but about
⅕ driving with “Sport” mode on). I’m totally convinced turning the TCS off on Mazda vehicles somehow makes the engine peppier and more efficient (or less unnecessary braking by TCS), hence improves gas mileage significantly!