3.5-4 stars (going with the optimistic rating)Book 1 was written under the name Susan Lyons, so look for "Sex Drive" under that title. Doesn't even seem related to the other 3 books in the series, not only because of the author's different name (Lyons and Foxes and Bears... oh my!), but also because there's no "Unexpectedly" in the title.After reading the 1st several pages, I thought this book was going to be cliched and tedious. But I kept reading, and once we got to the train trip, I started to enjoy it. Yes, Kat's constant inner monologue about not wanting to ruin her friendship with Nav gets a bit tedious and grating, but no more so than Nav's inability to just ask for what he wants. The idea to take on different identities is fun, but a little scary; Nav does a 180 turnabout by getting a whole new makeover to accomplish his goal. He also breaks out the trust fund bucks to finance it, so he's obviously serious about winning the girl.But being Pritam for 1 day & 1 night, and then Dhiraj for the remainder of the trip... again, fun, cool, slick, but sounds better on paper in a romance; in real life, it would just be ... creepy and scary. Here it's fun.What's a bit jarring is the author's insistence on keeping with her 1st person POV for the girl (Kat) and 3rd person POV for the guy (Nav), because we see and hear Kat through both 1st and 3rd perspectives. That seemed to work in the 1st book with Theresa/Tezzie and Damien, but here... not so sure about that particular writing device.The steam is hot and good. Not overdone. Not too out there, even with all the Kama Sutra talk; in fact, those positions make it more interesting.We also continue the overall story we started in book 1 with M&M's wedding plans (Merilee & Matt). And we get the continuity of the same email and phone conversations - interplay between the 4 sisters, which is good. We also get Kat's perspective on all of it, which deepens our understanding of both the sisters and how Kat perceives the conversations. The bigger picture is unfolding, one sister at a time.My nits:* I don't like the way that the parents are responsible for so much unrest and unhappiness in their daughters' lives. I understand the impact, but the author seems to allow the sisters to dump too much on their parents and not own up to taking charge of their own lives.* I also don't like how Theresa and Damien are completely relinquished to the background - that relationship. I get that Damien's on a book tour, so phone sex makes perfect sense. It's just... I miss hearing from Damien and not just from Theresa's POV.* Nav's parents... it seems as though this Kat-Nav relationship is going full-speed ahead, which is great. Except I wonder how it all fits with his parents? I can foresee lots of trouble if Nav doesn't give them the heads-up and soon.* And WHAT THE HECK is going on with Merilee? She's acting like a real spoiled brat - a Bridezilla. She seems to be overly afraid that her sisters are upstaging her. I understand she's felt left out of the threesome (or 3-pack) of sisters, but... Since Merilee's book is #4, if I get there, I suspect we'll find out what's really going on with her.