Chennai Central to Spencer Plaza (Anna Salai)

Yes, true!

I know it's a moot point for the OP, but there is a prepaid auto stand at the Central Train Station. You pay the guy in the booth four rupees, tell him where you're going, and he prints out a ticket telling the price (which is reasonable). Then an auto driver takes the ticket and takes you where you want to go--no haggling. Well, at least no haggling until you get to your destination, where the driver might ask you for a fare above the ticketed price, as happened to me this week. I said no very firmly, waved the ticket a bit ane walked away. Annoying, but relatively low on the "annoyed by auto drivers" scale.

...I'd forgotten about that pre-paid auto booth. I remember, now, reading about it in the newspaper, but have never used it

I think you'll be more annoyed by the Spencer Plaza shop owners.
Auto shouldnt cost you more than 40-50 Rs.
At 12pm you can take a bus.

If you are not lucky with Spencer Plaza take from there (TVS) Bus # 27D which goes to Citi Center Shopping Mall.

Spencers is more like a multi-storey bazaar, full (apart from one or two big stores) of gift shops, jewellery shops, electronics shops, everything shops.

Citi Centre (which I visited for the first time yesterday) is much more modern and western.

The Spencers shop owners can be very predatory.

Mute Point number two.
I took a cycle rickshaw. The poor bastard just gave up on the bridge and walked about a kilometre.
Who felt guilty?. MEEEEEE
He only asked 20 rupees.
Just made me feel worse.