SO I’VE WRITTEN A LOT ABOUT HYBRIDS, and I like mine — a couple of years ago I passed the Toyota Highlander Hybrid on to the Insta-Daughter and upgraded to a Lexus RX-450h, which is basically the Lexus version of the car I had before. My hybrids get great mileage in town — high thirties/low forties if you really try hard, low-to-mid thirties if you don’t — and do okay on the highway, getting around 27 or 28 in FKMPG (“Fred Krause Miles Per Gallon,” a measurement invented by a college friend; it’s what the car gets while going 80 with the air conditioning on “Max”).

InstaPundit reader Brad Stertz, who does communications for Audi, thinks I should give more attention to diesel technology, so they set me up with an Audi A8L TDI to drive to Florida, where I was already set to attend a law professors’ convention. The gimmick: I could go all the way there (a bit over 806 miles, door-to-door) on one tank of gas.

Of course, it’s a big tank: 23.8 gallons. But still, it gets 36 mpg in a really big car, and that’s pretty cool. I was happy to accept, and they dropped the car off a couple of days before we left. The version I got was quite posh, coming in at a sticker price of over $99,000. For that, you get such things as massaging seats, radar-controlled adaptive cruise control, all-around cameras, and more.

The massaging seats are very nice. It’s not like a Brookstone massage recliner, but they’re well-designed to ease the strain in your back over long drives. We drove straight back — a roughly 13 hour drive — and I appreciated them. There’s even built-in wi-fi, allowing you to surf the web from the front or from the cavernous back seat (the L in A8L means it’s stretched).

The all-around cameras offer an excellent view in parking — it looks like you’re seeing things from above the car, but the cameras are actually hidden in the bumpers and side-mirror housings.

The interior is beautifully done, something Audis are known for. (When I tested the HondaJet a while back, the interior designer for that plane told me that he was inspired by Audi car interiors). The super-premium Bang & Olufsen sound system sounded really nice, though a touch too high-endy for me — I think it may have been calibrated for aging Boomer ears.

The car is long — it wouldn’t fit in the slot in my garage where I usually keep the RX-8, and where the Toyota Highlander Hybrid fits comfortably; with the workbench at the front there wasn’t room. And I noticed that length in driving; I found myself unconsciously using chauffeur-moves to smooth curves, etc. (Strangely, it doesn’t look that big when parked). But on the Interstate it’s smooth and very comfortable to drive. The Insta-Wife, who was less enthusiastic about this test-drive than I was, quickly changed her tune. “This car is amazing,” she commented, shortly after taking the wheel for the first time.

The turbo-diesel has plenty of power for accelerating up on-ramps and the like, but loafs along at 1500 rpm at 80. The car tracks very smoothly (though there’s a warning device that vibrates the steering wheel if you cross a highway line without your turn signal being activated) and the steering is comfortable and not as numb as in many modern luxury vehicles. The “side assist” feature means that yellow lights flash in your side mirrors if there’s a car in your blind spot (more on that in a bit). And one feature that I haven’t properly appreciated turned out to be nice: The radar adaptive cruise control locks on to the car in front of you and maintains separation whether they speed up (up to the speed you’ve set on cruise) or slow down all the way to nothing. Creeping along in stop-and-go traffic near (where else) Atlanta, it was like being connected to the car ahead with an invisible cord. It actually makes long-distance driving a lot less tiring.

Criticisms: First, the Navigation system uses an annoying rotate-and-click knob to enter information; this is the same interface that was on an Audi A4 that we rented in LA last year, and it’s vastly inferior to, say, Lexus’s point-and-click interface. Second, somewhere in south Georgia the dash emitted a chime, the control panel said “Audi Side Assist — System Fault,” and the yellow lights in the side mirrors stopped working. The friendly Audi dealer in West Palm Beach fixed it posthaste (a matter of resetting a code) but it did make me wonder how well all this electronic wizardry will hold up. You might want to spring for the extended warranty.

Did we make it all the way on one tank? More or less. We made it to the end of the Florida Turnpike segment when I — as InstaPundit readers know, I’m usually cautious about fillups — finally cracked and tanked up. But the range calculator on the car was at that point showing enough fuel left to get me all the way to Miami, so I’m sure I could have made it to our hotel on what was left. And I think the fact that it only took one fillup each way reduced our travel time by a bit, which was nice.

The Insta-Wife and Insta-Daughter were big fans (Helen was surprised to find the car so easy to drive, and the Insta-Daughter, who worries about parking, wants that camera setup on her next car; she also loved the huge back seat and wi-fi), and were visibly sad when the folks came to take it away yesterday. If you’ve got close to $100K to spend on a car — or, if you’re a frugal type and want to forgo some of the bells and whistles, a mere $82K or so — you could do a lot worse.

Bottom Line: If long-distance highway cruising is your thing, this is a great car to do it in. It’s also a good deal cheaper than the comparable Lexus or Mercedes. And yes, I admit that diesels are a good gas-saving alternative to a hybrid, especially on long drives. You can’t argue with 36 mpg.

And does this mean more auto reviews on InstaPundit? Who knows? They’ve been more than occasional features here since the very earliest days of the blog. And they’re fun.