Without knowing more about the background of the case of the man killing a mother and baby, 16 months sounds pretty lenient. The Sentencing Advisory Panel's guidelines on causing death by dangeous driving suggest the following sentences:
1) a short custodial sentence for an offence arising from a momentary error of judgment or short period of bad driving, where there are no aggravating features;
2) a custodial sentence of 2-5 years when the standard of the offender�s driving is more highly dangerous, e.g. aggressive driving or greatly excessive speed, or when the offender has consumed alcohol or drugs;
3) a custodial sentence over 5 years, up to the maximum of 10 years, for the most serious offences, where the offender has driven with complete disregard for the safety of other road users and where other aggravating features are present.
If the second case mentioned is the one involving Robert Hendy-Freegard, he was convicted on two counts of kidnap, ten of theft and eight of deception. At present, UK law allows for a single case of kidnapping to be punishable by unlimited penalty.
While killing two people while driving illegally and then trying to avoid prosecution by fleeing the country is obviously reprehensible, unless there was proof the man had intended to kill mother and baby, it's an accident and punishable as such. Part of the reason kidnapping carries such a high sentence is the intent on the part of the kidnapper and the suffering caused to the victims.