What's the Name of That Book??? discussion

This is a horror novel I saw on a book shop shelf back in the 1990s, the blurb on the back stated (from memory) that it involved a vampire (or vampires) running amok on the California Zephyr (Not sure if this was the pre or post Amtrack train.)

But the real reason the novel stuck in my memory was the highly inappropriate cover picture which was of a British Rail Class 55 'Deltic' locomotive, rather than an American one.

Details of author/title are eagerly sought.

The description sounds like Mastery by Kelley Wilde.

A snippet from the Publisher's Weekly review:
...tale opens with a group of vampires practicing a nightmarish ritual of "mastery," which includes a technique for sipping the victim's blood like a fine wine. Next we meet (view spoiler)[ Dodge, an unusual and amusing private detective, (hide spoiler)]and several others who are journeying by train across country in 1986, the year of Halley's comet. Little do the passengers know (view spoiler)[that one of their companions is Austin Blacke, a renegade vampire who doesn't play even by the master vampires' rules. (hide spoiler)] And little do they know that, (view spoiler)[when the comet hits, (hide spoiler)] they'll take a train ride to San Francisco(view spoiler)[ in 1906, the year of the big earthquake. (hide spoiler)]

Also, if you search inside the book on Google Books, the word "zephyr" appears.
You can see a little bit of a train on the bottom of the cover.

That's it, I will admit in my memory the train was higher on the cover, and it's a bizarre choice by the cover designer. I also see on Amazon that the author has released a revised version called MonsterTime.

Thanks.