As I recall from reviews of the day, the Vixen with the diesel and manual (!?) usually pulled away from the stop sign trailing the delicate odor of cooked clutch. Not brisk off the line, so to speak.
A few years ago I read a fascinating page by a guy called Mr. Sharkey who had a converted electric Rabbit, he wanted more range. He made a diesel powered pusher trailer from the front end of a diesel Rabbit with a manual transmission (!?) which he controlled from the front car via a confabulated array of repurposed devices (for instance, a remote operated cordless drill to activate the clutch, driving a jack screw to press and let up on the clutch pedal!)
His site appears to be gone but an archived websnap is here:
Mr. Sharkey's Home Page | MrSharkey.Com
Fascinating stuff. He also used the diesel pusher to help along an ancient old RV that normally could barely sustain 45 motor down the road at a decent 55-60. If I can find more/better/more current details, I'll update this post.