Most expensive car I've seen in person is the Ferrari Enzo. It came into the bodyshop where my brother works at.

Most expensive car I've driven is an S55.

 

Which one of these has higher MSRP? I didn't realize the Reventon was so expensive - there was one on display at the Lamborghini dealership in London (South Kensington) and I walked by it several times last year. Heck, it may still be there. I've actually only ever seen one Veyron, parked outside some hotel in Paris.

 

Most expensive I've seen is the SLR McLaren 722 S Roadster, followed by the Ferrari Enzo.

Driven, can't remember what was the most expensive I've driven, but a few cars over 100K.

 

Seen: Bugatti Veyron
Driven: SL63 AMG

 

Never seen a Veyron so the most expensive I've seen is an Enzo. Driven? Mercedes Benz 560 SEC ($80k back in the 80's)

 

My neighbor had a Rolls Royce Phantom Drophead parked out front two weekends ago, then last weekend a Bentley Continental GT. Guess it helps to be an auto journalist.

But really the most expensive car I've ever seen would be some of the old one-of-a-kind or two-of-a-kind-but-they're-both-here Duesenbergs at the Classic Car Expo inside Oriental Palace in Vegas. Runner-up being the pair of Enzos that were at the Wynn one of the times I was there.

Sadly, the most expensive car I've ever driven was a C5 Corvette.

 

seen - enzo fxx in vegas
driven - isf

 

Seen: 2010 LP 560-4 UR turbo'd
Driven: 2005 XJ-R

 

Seen: McLaren F1
Driven: Mercedes S65 AMG

 

good question. i think the veyron are all well over mil now. reventon, i could be wrong, but always think there is a price but not so much about the market. and i wonder if the aventador is affecting the price

 

Seen Veyron
Driven GT2 RS

 

Seen:

Veyron, EB110, Rolls Phantom

Driven:

1997 Mercedes CL 600. It was previously owned by Michael Richards of "Seinfeld" fame

 

seen? just about everything.
driven? loaded 911 turbo cabriolet (about $150k) - car was ridiculously fast.

 

Saleen s7 most expensive seen, and maserati quattroporte or ferrari 430 most expensive that i've driven, not bad for 2 years of drive, to bad it was only about for a mile or so in either car haha

 

Seen? That's a tough one. Being a race official, I've been up close and personal to some pretty exotic racecars, both modern and vintage (and sometimes crumpled up into a little ball ). Would probably have to say, the most expensive, I've seen in person (and helped push), would be an LMP or F1 car.

Street car? Again, seen some pretty rare and/or expensive stuff at or vintage races and car show here in Pittsburgh.
(shameless plug for for an event I'm deeply involved in - Pittsburgh Vintage Grand Prix)

Been inside of? Rode shotgun for a few hot laps in a vintage GT-40 with documented LeMans racing history. That was a rush

Driven? Jag XK120, E-type, or maybe an Aston DB-5? Don't know what the value on any of them were, but I got to drive a lot of vintage European stuff when I worked for a family friend who serviced and restored them (great summer job!)