I drove into the city and realized the floor between my gas pedal and my seat
Was wet. I felt it was oil. I know I will have to make an appt with the mechanic,
But I thought I could get a heads up on it so I don't get taken advantage of.

There is nothing there that would be oil. Spill something? Heater cores are usually on the passenger side. Possible master cylinder leak but that would be under the dash. Maybe windshield washer fluid?

Unless you have a mechanical oil pressure gauge (means its got to be a really old vehicle) or an older Mercedes Diesel... (ruptured diaphram on the shutoff solenoid would send oil up to the ignition switch area and make an ugly black mess.

With what little information you gave we really can do much but guess... you didn't describe the liquid or even tell us what kind of car it is and year.

If you can't fix it yourself you are open to being taken advantage of. Sorry but that's just how it is and why some of us fix our own stuff (besides the fact we know how to).

I could be coolant.
What vehicle is this?

I can't fix cars... I'm a senior who has had the car for three years but bought
It from my roommate whose Mom died.. it's a 2000 malibu chevy with only
41,000 orig miles (her mom only took it to garden clubs.. living in a small
Town, never went anywhere) I'm at the mercy of the mechanic

2000 chevy malibu... 41K miles (belong to someone in her late 80's who
Hardly drove it) I'm off to the mechanic... hope he doesn't soak me.

I have actually seen this before. Oil can wick itself through an engine wiring harness into the dash harness.
In my case oil bypassed through an internally leaking cam position sensor right into the interior cabin landing on the passengers feet. This is where it ended at the ecm behind the glovebox.
So it is possible it's actually engine oil. Stranger things have happened in the car biz.