2007 Mazda 3 decelerating much faster while coasting, like brakes are being applied

[maximus86]

A few days ago I noticed my 2007 Mazda 3 felt like the brakes were dragging. I took it into the shop and the mechanic replaced the front brake rotors and pads and sent me on my way. The problem seemed to be gone. A few days later I noticed the same thing happening again so I took it back to the same mechanic. He lifted the car for me and spun all the wheels to show me there was no drag. When we went on a test drive for me to show him we both noticed the car glided smoothly when we were driving down the road and the gear was put in neutral, the way it felt a week ago. When we put t back into drive gear, the car immediately starts to slow down as if the brakes are gently being applied. He said it is probably a transmission issue but he doesn't work on transmissions. Any mechanic I call in my area doesn't want to work on the transmission. What do I do and has anyone had this problem before? I have 170,000 km.

[maximus86]

Also to add my fuel economy as noticeably declined.

[morganc]

Start with a tranny flush. You might also want to clean your throttle body. Restriction could be starving the engine when the throttle plate is closed.

[jeff7670]

Automatic or manual transmission?

[mazdasport]

Fuel economy could be related to most gas stations using winter fuel mixed with additives to stop water and such from building up in tanks

[maximus86]

Automatic or manual transmission?

Automatic

[maximus86]

Start with a tranny flush. You might also want to clean your throttle body. Restriction could be starving the engine when the throttle plate is closed.

Is cleaning the throttle body expensive?

[JonsMazda]

Is cleaning the throttle body expensive?

It's easy! You can DIY. Watch youtube clips on cleaning mazda 3 throttlebody.

[TheMAN]

is your A/C on? This will cause the "drag"
A/C will turn on in the defroster mode

[kaleshnikov]

Have you checked the quality of your transmission fluid? Check it using your dipstick, ideally after the car has been driven for 15-30min and you're back in idle. Leave the engine on, and check it using a clean cloth. Wipe it a few times and see how black it is and whether it smells burnt. If you see any metallic flaking or burning smell, quite possible you're having transmission issues and doing a fluid change/flush MAY cause your transmission to slip.

Have you tried to see if the car does the same if you manually select the gears using the tiptronic?

Are your revs high and possibly the car is stuck in a lower gear?

Next, have you checked if there are any codes stored in the ECU? Could be some transmission sensors involved in this if all else shows OK above.

Depending on your mechanic, some are more thorough than others when they service brakes. It's important to ask if he cleaned the caliper pins, re greased them (using silicone) and everything else. Some shops will slap on pads and rotors and get you out the door without having touched any of the pins and boots.