I have had 3 cars put on auto LPG over the last 6 years for about rs. 20-21 k each in mumbai
this assumes a breakeven of about rs. 1/km so around 22, 000 km to recover the kit cost before you start actually saving money
all 3 cars were automatic so there is no impact on the transmission [obviously]
all had MPFI [multi point fuel injection] which usually has more problems than simpler carburetors
the City AT had the least problems of the 3 so far [old model]
the Corolla had the most so you might want to avoid adding LPG if you have a Toyota
we had morning start problems for months on end [multiple tries with revving the pedal] despite multiple visits to the workshop in chembur
since we end up almost exclusively driving on LPG the Corolla petrol fuel injector gets clogged with rust and needs cleaning 2-3 times a year which can be reduced by simply driving more on petrol
since the Sonata had a v6 it needed an extra device for rs. 1, 500 for delivering enough gas to the larger 2.7 L engine compared to the other regular 4 cylinder cars
i prefer LPG to CNG because:
its cheaper by about rs. 15 k to install
its lighter by about 50kg which impacts mileage
its filled at a lower pressure about 10-11 bars instead of almost 190-200 bar for CNG
this reduces any chances of leaks which can be a safety issue
it takes half the time to refuel at a pump compared to CNG
it recovers your investment quicker for the majority of cars that do smaller distances of around 1, 000 miles or 1, 600 km / month compared to CNG or diesel which need almost 2, 000 km monthly to make economic sense
shorter lines at the pump than CNG [even though the queue for cars is different from autos etc.]
remember if you do less than 1, 000 km / month or 12, 000 km annually you should simply continue with petrol since that’s cheaper to run over the next 3-4 years at which point you might replace your car in any case
but you should decide based on which type of fuel is available near your home or work obviously
if your car is still under warranty, do NOT put any CNG/LPG kit since it will void your manufacturer warranty and that’s a risk you should avoid in case of any claims in the initial 1-2 years of ownership
kindly note that all 3 of my cars were sedans over 100 bhp - if you need the boot space, don’t install any kit in your hatchback or simply put a roof rack for your bags instead
also there is a loss of power in LPG so don’t put it on engines below 100 bhp else you will notice it when your AC is running and this requires a change in your driving style which is harder than it sounds since you won’t be able to do as much overtaking as on petrol
you do have a switch inside so you can recover some of the power loss of LPG / CNG when you need to
to sum up, here is my rule of thumb for those of you still debating:
1] switch to lpg from petrol if you do over 15, 000 km per year
2] switch to CNG if you do over 20, 000 km annually
3] diesel if you do over 25, 000 km
4] if you do less than 12, 000 km then you should CHOOSE petrol over all other fuels!
not just for people stuck with petrol ...
else it does not make financial sense even at current high rates at the pump