Cleaning out the crap in your car - $0

Other Floridians might agree:

This mostly a pre-airbag thing, but a new steering wheel. The one thing that you touch every second you’re in the car.

Definitely the Fuel Shark

And to all the conservative nutbags who but truck nuts on their car, you just performed gender re-assignment surgery, and have therefore admitted that gender is fluid and you should stop voting Republican.

Since the vast majority of drivers aren’t concerned with performance - not in a meaningful way, other than “can I get around this asshat before I miss my exit”, and since 75% of you are saying tires (because, well, yeah):

Anything that makes your daily drive easier or more enjoyable. And this is going to be different…

For performance purposes, and after tires, brakes, safety stuff, if you have a modern turbo car, an ECU flash. It’s almost unbelievable to me as a somewhat-old-timer that you can pay $500, plug a TV remote into your dash, press a button and come out making 50hp and 100lb-ft more and sometimes still be covered under…

I had one for a 2015 WRX and I got one for a 2016 981S using the Stage 1/93 octane map, I can say it is noticeably more powerful with more linear acceleration and the power band comes on about 500-800 RPM sooner. Well worth the money.

Tires is usually the number one answer to this. While I usually wouldn’t disagree, this time I will.

If it’s a Fox-body Mustang, then I’d say brakes would be the best upgrade.

Other than the obvious that has been said 1000000x (wheels and tires). With almost all modern performance cars being turbo’d, tunes are the easiest bang for buck to make significantly more HP and TQ.

What if I told you that you could shave 20 pounds off the center of gravity for the car for nothing?

Best bang for your buck? Dinan makes a sport tuner for basically any modern-ish BMW, Mini, and Mercedes 2.0 and 3.0 engines. Plugs right in with no labor cost, adds 30-40 hp, costs $250-300, and you can move it to a different car if you want to sell the car or the tuner.

Sway bars, especially for a FWD car. That is if you care about handling at all.

Yeah, tires is definitely first. Then Rain-X. Then remove all the visual obstructions from the windshield and dash.

Did the same bushings and a Mountune shift pivot linkage on my Focus ST.  Huge difference in shift feel.  Just got done with the full RS brake kit and Mountune adjustable Konis/springs.  Braking/handling are sports car quality now.  Pair that with 255 width Potenza Sport tires and about 45 lbs of sound dampening…

Most modern cable actuated manual transmissions can have a short shift adapter and metal bushings installed onto the shift plate for like $100 and an hour. This was the single best mod for my Fiesta ST. 

When I first got my ‘68 Cutlass, it had an Olds 350 V8, which soon developed a knock. After some research, I quickly learned that parts for a 350 rebuild were roughly the same price as parts for rebuilding an Olds big block, so I got a 425 Olds from a junkyard and rebuilt that instead. Not that much more money, big…

A good tune is typically right up there.

Synthetic oil.