Lots of good choices for sure in this segment now! And every car brings something unique to the table.

Mercedes C-Class

What you'll like:
- Stunning looks & design . Matched to solid build quality too
- Premium quality interiors, supportive seats, filled with technology
- Useable rear seat, with better legroom than before
- Wide range of engines; powerful 265-hp C300d for enthusiasts, workhorse C220d and a C200 for sedate drivers
- Smooth & competent 9-speed AT gearbox
- Well-damped suspension offers mature ride quality
- Fun to drive (with the right engine)! Communicative chassis & excellent high-speed manners
- The C220d (especially) & C200k are reasonably fuel-efficient for the segment
- Equipment such as seat kinetics, latest-gen MBUX, panoramic sunroof, memory seats, electric steering adjustment…
- Top notch safety kit, runflat tyres, powerful brakes & a suite of electronic aids to keep you safe
What you won't:
- C200 petrol’s 1.5L drivetrain feels just about adequate. Best for chauffeured use or for calm owners
- There is no bigger or more powerful petrol engine option (like the C300d)
Rs 55 - 61 lakh ex-showroom pricing is stiff! We find it overpriced - Boot space (already at a premium) is drastically impacted by the spare wheel on the floor
Better as a 4-adult seater than 5 - BMW’s 330i is the more fun-to-drive petrol sedan
- IMHO, the faux leather seats just don't cut it at this price point (3-Series gives real leather). No ventilated seats either
- Styling is more of an evolution than a revolution. Also, looks very similar to other sedans in the Mercedes range
- While it’s not unusual for premium sedans, you need to be careful on bad bumps. This car with 4 people and luggage bottomed out a few times during our Mussoorie drive
Link to Official Review
BMW 3 Series

What you'll like:
- Just the right size for a luxury sedan for India
- Punchy rev-happy engine & well-tuned gearbox deliver superb performance
- Great combination of ride and handling; just how a 3 Series should be
- Big step up in interior quality & design (from the F30)
- Loaded with tech, new style speedometer & more. iDrive 7 is nice to use
What you won't:
- Sad boot space with the spare wheel underneath
- Features like keyless entry, HUD, Adaptive LEDs are expected at this price
- Rs. 47 - 53 lakh price is stiff, although fat dealer discounts are available
- Fake engine noise piped in; tad too fake for our taste
Link to official review
Audi A4

Link to BHPian sauravpat's Ownership Review
Volvo S60

What you'll like:
- Astonishingly handsome styling! The Volvo S60 looks absolutely fabulous
- Solid build quality is very satisfying
- Sweet-looking cabin that’s loaded to the gills with features. Has sufficient room too
- Spectacular Harman Kardon sound system. Easily the best ICE in the segment
- Smooth & peppy 2.0L turbo-petrol engine mated to a competent 8-speed AT
- Sorted ride & handling. The S60's high speed stability is excellent too
- Euro NCAP's 5-star safety rating & loads of tech like adaptive cruise control, pilot assist, lane-keeping aid, collision mitigation support (front) etc.
- Depth of engineering that is as good as the best from Germany
What you won't:
- A FWD car in a segment where RWD is the norm
- Power & torque figures are lower than the competition
- No diesel engine on offer with the Volvo S60. Those with high running will look elsewhere
- The rear seat is placed too low, under-thigh support is poor and the floor hump is too big
- The S60 is missing some features like paddle shifters, 360-degree camera, cooled seats...
- Volvo's thin dealer network in India
- To many people, the Volvo brand doesn't have the badge cachet of the German marques
- Not as exhilarating to drive as the BMW 330i which is the segment benchmark
Link to official review
BMW M340i xDrive

What you'll like:
- Ferocious 6-cylinder turbo-petrol motor with 382 BHP on tap! Lives for 7,000 rpm
- All-wheel-drive gives the BMW M340i leech-like grip & solid stability levels
- Sporty, well-tuned exhaust note is addictive at high revs
- The ZF 8-speed AT is the best gearbox in the segment. Fast & smooth
- 0 – 100 in 4.4 seconds with 4-door everyday practicality. Go touring with the family!
- Lovely cabin, premium build, very supportive seats & a fab driving position
- BMW’s strong track record for reliability (among the luxury marques)
- 5-star NCAP rating, awesome brakes & a laundry list of safety equipment
What you won't:
- Ride is much firmer than a regular 3-Series. Liveable, but you feel everything on the road
- Sad boot space with a spare wheel
- We don’t like the radiator grille, same rim design (as the 330i) and gunmetal-coloured ORVMs
- Rear floor hump is enormous! Car is better as a 4-seater than 5
- Your fuel costs will be a lot higher than say, a 530d
- Runflat tyres come with many compromises, wear out soon & are expensive to replace
- We hate the all-digital instrument console. Also, the rev counter is weirdly inverted
- Some irritants such as the lack of keyless entry (!!!), w-i-d-e 6 meter turning radius & annoying speed warnings
Link to official review.
Lexus ES

What you'll like:
- Funky styling stands out from the crowd. Decently priced for a CBU too (imported as is from Japan)
- Hybrid powertrain with good low-end torque and a butter-smooth CVT gearbox
- Very good for city usage due to mileage and comfort offered
- Loaded with kit (heated and ventilated front seats, 17-speaker sound system, heated and reclinable rear seats)
- Lexus' track record of reliability & exemplary customer service
What you won't:
- Weird front styling not to everyone's taste
- Not as much fun to drive as its German competitors
- CVT can get lazy & noisy with a heavy right foot
- Unintuitive infotainment system with a touchpad that is poorly positioned for a right-hand drive vehicle
- Tiny sales network. Period
Link to drive report.
Audi A6

Link to BHPian hrk997's Ownership Review
Here's what GTO had to say on the matter:
Lots of good choices for sure in this segment now! And every car brings something unique to the table. My vote is simple:
Diesel = C300 AMG. Absolutely love what Mercedes has done with the new C-Class. The styling, interiors, it's more fun-to-drive, adults can now actually sit on the rear seat and that 9-speed gearbox.
Petrol = M340i for just 5 lakhs more than the C300. This car is a monster; more power than you'd ever need on Indian roads, leech-like grip and daily-driver usability.
If my running was a lot (2000+ km / month), I'd get the C300 as powerful diesels give you the best of both worlds (performance + efficiency). But my running isn't that high and I can live with 4 kmpl, hence it's the M340i for me.
Here's what BHPian karan561 had to say on the matter:
Wait a minute ! With almost 14 months of ownership of the M340i I have NEVER witnessed a 4 km/l figure. In Mumbai City, with mixed driving / mild traffic one can easily achieve anywhere between 6.5 to 9 km/l. In fact on highways when driven well it can achieve 14 - 15 km/l too.
Here are a few examples:

14 km/l on a 200 kms stretch achieved by a M340i owner in our group:

Another one of our group cars achieved 15.6 km/l over a 250km stretch:

Note: Its an M340i but has an Alpina cluster coded.
Note: Didn't mean to go off topic but that 4 kmpl figure can be misleading hence thought i'll contribute/clarify.
Read BHPian comments for more insights and information.